Removing more from the no-op proto-gen-validate build (#738)

before
-rwxr-x--- 1 alyssar primarygroup 23338512 Nov 21 17:00
bazel-bin/test/performance/test_binary_size_stripped
-rwxr-x--- 1 alyssar primarygroup 23M Nov 21 17:00
bazel-bin/test/performance/test_binary_size_stripped
after
-rwxr-x--- 1 alyssar primarygroup 19642512 Nov 21 17:04
bazel-bin/test/performance/test_binary_size_stripped
-rwxr-x--- 1 alyssar primarygroup 19M Nov 21 17:04
bazel-bin/test/performance/test_binary_size_stripped

Proof of concept use here:
envoyproxy/envoy#24151 which is passing all
Envoy Mobile CI (its failing Envoy CI because of the dependency check
which is expected and irrelevant)

templates/ccnop/file.go

@@ -25,10 +25,8 @@ using std::string;
 } // namespace
 {{ end }}
 
-#define X_{{ .Package.ProtoName.ScreamingSnakeCase }}_{{ .File.InputPath.BaseName | screaming_snake_case }}(X) \
 {{ range .AllMessages -}}
 {{- if not (ignored .) -}}
-	X({{class . }}) \
 {{ end -}}
 {{ end }}
 `
@@ -37,19 +35,8 @@ const moduleFileTpl = `// Code generated by protoc-gen-validate
 // source: {{ .InputPath }}
 // DO NOT EDIT!!!
 
-#include "{{ output .File ".validate.h" }}"
-
 namespace pgv {
 namespace validate {
-using std::string;
-
-{{ range .AllMessages }}
-{{- if not (ignored .) -}}
-{{- if not (disabled .) -}}
-pgv::Validator<{{ class . }}> {{ staticVarName . }}(static_cast<bool(*)(const {{ class .}}&, pgv::ValidationMsg*)>({{ package .}}::Validate));
-{{- end -}}
-{{ end }}
-{{ end }}
 
 } // namespace validate
 } // namespace pgv