[grpc][Gpr_To_Absl_Logging] Disable the ConfigVar because it wont work anymore. (#36761)

Disable the ConfigVar because it wont work anymore.
As on 30 May 2024, about 40% of the instances of gpr_log are migrated to absl LOG.
The remaining instances will be migrated soon.
Given this situation, it would be a little weird to keep this ConfigVar.
Because half the things will log via gpr_log and the others will log through LOG directly.
For the same reason, the platform specific logging code has been deleted. https://github.com/grpc/grpc/pull/36120
This needs to be deleted too.

Closes #36761

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/36761 from tanvi-jagtap:grpc_trace f2f987e625
PiperOrigin-RevId: 638893208

src/core/lib/config/config_vars.cc

@@ -75,8 +75,6 @@ ABSL_FLAG(absl::optional<bool>, grpc_not_use_system_ssl_roots, {},
           "Disable loading system root certificates.");
 ABSL_FLAG(absl::optional<std::string>, grpc_ssl_cipher_suites, {},
           "A colon separated list of cipher suites to use with OpenSSL");
-ABSL_FLAG(absl::optional<bool>, grpc_absl_logging, {},
-          "Use absl logging from within gpr_log.");
 
 namespace grpc_core {
 
@@ -94,8 +92,6 @@ ConfigVars::ConfigVars(const Overrides& overrides)
       not_use_system_ssl_roots_(LoadConfig(
           FLAGS_grpc_not_use_system_ssl_roots, "GRPC_NOT_USE_SYSTEM_SSL_ROOTS",
           overrides.not_use_system_ssl_roots, false)),
-      absl_logging_(LoadConfig(FLAGS_grpc_absl_logging, "GRPC_ABSL_LOGGING",
-                               overrides.absl_logging, true)),
       dns_resolver_(LoadConfig(FLAGS_grpc_dns_resolver, "GRPC_DNS_RESOLVER",
                                overrides.dns_resolver, "")),
       verbosity_(LoadConfig(FLAGS_grpc_verbosity, "GRPC_VERBOSITY",
@@ -147,8 +143,7 @@ std::string ConfigVars::ToString() const {
       "\"", ", default_ssl_roots_file_path: ", "\"",
       absl::CEscape(DefaultSslRootsFilePath()), "\"",
       ", not_use_system_ssl_roots: ", NotUseSystemSslRoots() ? "true" : "false",
-      ", ssl_cipher_suites: ", "\"", absl::CEscape(SslCipherSuites()), "\"",
-      ", absl_logging: ", AbslLogging() ? "true" : "false");
+      ", ssl_cipher_suites: ", "\"", absl::CEscape(SslCipherSuites()), "\"");
 }
 
 }  // namespace grpc_core

src/core/lib/config/config_vars.h

@@ -38,7 +38,6 @@ class GPR_DLL ConfigVars {
     absl::optional<bool> enable_fork_support;
     absl::optional<bool> abort_on_leaks;
     absl::optional<bool> not_use_system_ssl_roots;
-    absl::optional<bool> absl_logging;
     absl::optional<std::string> dns_resolver;
     absl::optional<std::string> verbosity;
     absl::optional<std::string> stacktrace_minloglevel;
@@ -103,8 +102,6 @@ class GPR_DLL ConfigVars {
   bool NotUseSystemSslRoots() const { return not_use_system_ssl_roots_; }
   // A colon separated list of cipher suites to use with OpenSSL
   absl::string_view SslCipherSuites() const { return ssl_cipher_suites_; }
-  // Use absl logging from within gpr_log.
-  bool AbslLogging() const { return absl_logging_; }
 
  private:
   explicit ConfigVars(const Overrides& overrides);
@@ -114,7 +111,6 @@ class GPR_DLL ConfigVars {
   bool enable_fork_support_;
   bool abort_on_leaks_;
   bool not_use_system_ssl_roots_;
-  bool absl_logging_;
   std::string dns_resolver_;
   std::string verbosity_;
   std::string stacktrace_minloglevel_;

src/core/lib/config/config_vars.yaml

@@ -126,8 +126,3 @@
     ECDHE-ECDSA-AES256-GCM-SHA384:\
     ECDHE-RSA-AES128-GCM-SHA256:\
     ECDHE-RSA-AES256-GCM-SHA384"
-- name: absl_logging
-  type: bool
-  default: true
-  description:
-    Use absl logging from within gpr_log.