Revert "Run git gc periodically (#564)" (#615)

Motivation:
We no longer need Git gc because we are going to provide a way to remove old commits.
#575

Modifications:
- Revert Git gc.

Result:
- This reverts commit e6caf26.

server/src/main/java/com/linecorp/centraldogma/server/CentralDogmaBuilder.java

@@ -119,13 +119,9 @@ public final class CentralDogmaBuilder {
     private String sessionValidationSchedule = DEFAULT_SESSION_VALIDATION_SCHEDULE;
     @Nullable
     private Object authProviderProperties;
-
     private int writeQuota;
     private int timeWindowSeconds;
 
-    @Nullable
-    private RepositoryGarbageCollectionConfig repositoryGarbageCollection;
-
     /**
      * Creates a new builder with the specified data directory.
      */
@@ -524,18 +520,6 @@ public CentralDogmaBuilder writeQuotaPerRepository(int writeQuota, int timeWindo
         return this;
     }
 
-    /**
-     * Sets the minimum required number of commits newly added to run a garbage collection and the
-     * <a href="https://www.quartz-scheduler.org/documentation/quartz-2.3.0/tutorials/crontrigger.html">
-     * Quartz cron expression</a> when garbage collections is suppose to be triggered.
-     */
-    public CentralDogmaBuilder repositoryGarbageCollection(int minNumNewCommits, String schedule) {
-        checkArgument(minNumNewCommits > 0, "minNumNewCommits: %s (expected: > 0)", minNumNewCommits);
-        requireNonNull(schedule, "schedule");
-        repositoryGarbageCollection = new RepositoryGarbageCollectionConfig(minNumNewCommits, schedule);
-        return this;
-    }
-
     /**
      * Returns a newly-created {@link CentralDogma} server.
      */
@@ -569,6 +553,6 @@ private CentralDogmaConfig buildConfig() {
                                       maxRemovedRepositoryAgeMillis, gracefulShutdownTimeout,
                                       webAppEnabled, webAppTitle, mirroringEnabled, numMirroringThreads,
                                       maxNumFilesPerMirror, maxNumBytesPerMirror, replicationConfig,
-                                      null, accessLogFormat, authCfg, quotaConfig, repositoryGarbageCollection);
+                                      null, accessLogFormat, authCfg, quotaConfig);
     }
 }

server/src/main/java/com/linecorp/centraldogma/server/CentralDogmaConfig.java

@@ -138,9 +138,6 @@ public final class CentralDogmaConfig {
     @Nullable
     private final QuotaConfig writeQuotaPerRepository;
 
-    @Nullable
-    private final RepositoryGarbageCollectionConfig repositoryGarbageCollection;
-
     CentralDogmaConfig(
             @JsonProperty(value = "dataDir", required = true) File dataDir,
             @JsonProperty(value = "ports", required = true)
@@ -168,9 +165,7 @@ public final class CentralDogmaConfig {
             @JsonProperty("csrfTokenRequiredForThrift") @Nullable Boolean csrfTokenRequiredForThrift,
             @JsonProperty("accessLogFormat") @Nullable String accessLogFormat,
             @JsonProperty("authentication") @Nullable AuthConfig authConfig,
-            @JsonProperty("writeQuotaPerRepository") @Nullable QuotaConfig writeQuotaPerRepository,
-            @JsonProperty("repositoryGarbageCollection")
-            @Nullable RepositoryGarbageCollectionConfig repositoryGarbageCollection) {
+            @JsonProperty("writeQuotaPerRepository") @Nullable QuotaConfig writeQuotaPerRepository) {
 
         this.dataDir = requireNonNull(dataDir, "dataDir");
         this.ports = ImmutableList.copyOf(requireNonNull(ports, "ports"));
@@ -224,7 +219,6 @@ public final class CentralDogmaConfig {
                                           ports.stream().anyMatch(ServerPort::hasProxyProtocol));
 
         this.writeQuotaPerRepository = writeQuotaPerRepository;
-        this.repositoryGarbageCollection = repositoryGarbageCollection;
     }
 
     /**
@@ -462,16 +456,6 @@ public QuotaConfig writeQuotaPerRepository() {
         return writeQuotaPerRepository;
     }
 
-    /**
-     * Returns the {@link RepositoryGarbageCollectionConfig} for
-     * cleanuping unnecessary files and optimizing {@link Repository}s.
-     */
-    @Nullable
-    @JsonProperty("repositoryGarbageCollection")
-    public RepositoryGarbageCollectionConfig repositoryGarbageCollection() {
-        return repositoryGarbageCollection;
-    }
-
     @Override
     public String toString() {
         try {

server/src/main/java/com/linecorp/centraldogma/server/internal/storage/repository/RepositoryWrapper.java

@@ -196,16 +196,6 @@ public <T> CompletableFuture<MergedEntry<T>> mergeFiles(Revision revision, Merge
         return unwrap().mergeFiles(revision, query);
     }
 
-    @Override
-    public Revision gc() throws Exception {
-        return unwrap().gc();
-    }
-
-    @Override
-    public Revision lastGcRevision() {
-        return unwrap().lastGcRevision();
-    }
-
     @Override
     public String toString() {
         return Util.simpleTypeName(this) + '(' + unwrap() + ')';