scalar: remove stale config values

These config values were added in the original Scalar contribution,
d0feac4 (scalar: 'register' sets recommended config and starts
maintenance, 2021-12-03), but were never fully checked for validity in
the upstream Git project. At the time, Scalar was only intended for the
contrib/ directory so did not have as rigorous of an investigation.

Each config option has its own justification for removal:

* core.preloadIndex: This value is true by default, now. Removing this
  causes some changes required to the tests that checked this config
  value. Use gui.gcwarning=false instead.

* core.fscache: This config does not exist in the core Git project, but
  is instead a config option for a Git for Windows feature.

* core.multiPackIndex: This config value is now enabled by default, so
  does not need to be called out specifically. It was originally
  included to make sure the background maintenance that created
  multi-pack-indexes would result in the expected performance
  improvements.

* credential.validate: This option is not something specific to Git but
  instead an older version of Git Credential Manager for Windows. That
  software was replaced several years ago by the cross-platform Git
  Credential Manger so this option is no longer needed to help users who
  were on that older software.

* pack.useSparse=true: This value is now Git's default as of de3a864
  (config: set pack.useSparse=true by default, 2020-03-20) so we don't
  need it set by Scalar.

Signed-off-by: Derrick Stolee <stolee@gmail.com>

Author: derrickstolee

scalar.c

@@ -129,9 +129,6 @@ static int set_recommended_config(int reconfigure)
 	struct scalar_config config[] = {
 		/* Required */
 		{ "am.keepCR", "true", 1 },
-		{ "core.FSCache", "true", 1 },
-		{ "core.multiPackIndex", "true", 1 },
-		{ "core.preloadIndex", "true", 1 },
 #ifndef WIN32
 		{ "core.untrackedCache", "true", 1 },
 #else
@@ -151,7 +148,6 @@ static int set_recommended_config(int reconfigure)
 #endif
 		{ "core.logAllRefUpdates", "true", 1 },
 		{ "credential.https://dev.azure.com.useHttpPath", "true", 1 },
-		{ "credential.validate", "false", 1 }, /* GCM4W-only */
 		{ "gc.auto", "0", 1 },
 		{ "gui.GCWarning", "false", 1 },
 		{ "index.skipHash", "true", 1 },
@@ -160,7 +156,6 @@ static int set_recommended_config(int reconfigure)
 		{ "merge.stat", "false", 1 },
 		{ "merge.renames", "true", 1 },
 		{ "pack.useBitmaps", "false", 1 },
-		{ "pack.useSparse", "true", 1 },
 		{ "receive.autoGC", "false", 1 },
 		{ "feature.manyFiles", "false", 1 },
 		{ "feature.experimental", "false", 1 },

t/t9210-scalar.sh

@@ -202,15 +202,15 @@ test_expect_success 'scalar clone --no-... opts' '
 test_expect_success 'scalar reconfigure' '
 	git init one/src &&
 	scalar register one &&
-	git -C one/src config core.preloadIndex false &&
+	git -C one/src config unset gui.gcwarning &&
 	scalar reconfigure one &&
-	test true = "$(git -C one/src config core.preloadIndex)" &&
-	git -C one/src config core.preloadIndex false &&
+	test false = "$(git -C one/src config gui.gcwarning)" &&
+	git -C one/src config unset gui.gcwarning &&
 	rm one/src/cron.txt &&
 	GIT_TRACE2_EVENT="$(pwd)/reconfigure" scalar reconfigure -a &&
 	test_path_is_file one/src/cron.txt &&
-	test true = "$(git -C one/src config core.preloadIndex)" &&
-	test_grep "preloadIndex = true # set by scalar" one/src/.git/config &&
+	test false = "$(git -C one/src config gui.gcwarning)" &&
+	test_grep "GCWarning = false # set by scalar" one/src/.git/config &&
 	test_grep "excludeDecoration = refs/prefetch/\* # set by scalar" one/src/.git/config &&
 
 	test_subcommand git maintenance start <reconfigure &&
@@ -234,14 +234,14 @@ test_expect_success 'scalar reconfigure --all with includeIf.onbranch' '
 		git init $num/src &&
 		scalar register $num/src &&
 		git -C $num/src config includeif."onbranch:foo".path something &&
-		git -C $num/src config core.preloadIndex false || return 1
+		git -C $num/src config unset gui.gcwarning || return 1
 	done &&
 
 	scalar reconfigure --all &&
 
 	for num in $repos
 	do
-		test true = "$(git -C $num/src config core.preloadIndex)" || return 1
+		test false = "$(git -C $num/src config gui.gcwarning)" || return 1
 	done
 '
 
@@ -257,7 +257,7 @@ test_expect_success 'scalar reconfigure --all with detached HEADs' '
 		rm -rf $num/src &&
 		git init $num/src &&
 		scalar register $num/src &&
-		git -C $num/src config core.preloadIndex false &&
+		git -C $num/src config unset gui.gcwarning &&
 		test_commit -C $num/src initial &&
 		git -C $num/src switch --detach HEAD || return 1
 	done &&
@@ -266,7 +266,7 @@ test_expect_success 'scalar reconfigure --all with detached HEADs' '
 
 	for num in $repos
 	do
-		test true = "$(git -C $num/src config core.preloadIndex)" || return 1
+		test false = "$(git -C $num/src config gui.gcwarning)" || return 1
 	done
 '
 
@@ -298,7 +298,7 @@ test_expect_success 'scalar supports -c/-C' '
 	git init sub &&
 	scalar -C sub -c status.aheadBehind=bogus register &&
 	test -z "$(git -C sub config --local status.aheadBehind)" &&
-	test true = "$(git -C sub config core.preloadIndex)"
+	test false = "$(git -C sub config gui.gcwarning)"
 '
 
 test_expect_success '`scalar [...] <dir>` errors out when dir is missing' '