[Pipeline] Remove Annotation2Metadata pass in post-link pipelines

[aeubanks]

Summary

The pre-link pipeline already ran the pass and it only needs to be run once.

[aeubanks]

tests

[nikic]

LGTM

llvm/lib/Passes/PassBuilderPipelines.cpp

PassBuilder::buildThinLTOPreLinkDefaultPipeline(OptimizationLevel Level) {
 
   return MPM;
 }
 
 ModulePassManager PassBuilder::buildThinLTODefaultPipeline(
     OptimizationLevel Level, const ModuleSummaryIndex *ImportSummary) {
   ModulePassManager MPM;
 
-  // Convert @llvm.global.annotations to !annotation metadata.
-  MPM.addPass(Annotation2MetadataPass());
-
   if (ImportSummary) {
     // These passes import type identifier resolutions for whole-program
     // devirtualization and CFI. They must run early because other passes may
     // disturb the specific instruction patterns that these passes look for,
     // creating dependencies on resolutions that may not appear in the summary.
     //
     // For example, GVN may transform the pattern assume(type.test) appearing in
     // two basic blocks into assume(phi(type.test, type.test)), which would
return buildPerModuleDefaultPipeline(Level,
                                        /* LTOPreLink */ true);
 }
 
 ModulePassManager
 PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level,
                                      ModuleSummaryIndex *ExportSummary) {
   ModulePassManager MPM;
 
-  // Convert @llvm.global.annotations to !annotation metadata.
-  MPM.addPass(Annotation2MetadataPass());
-
   for (auto &C : FullLinkTimeOptimizationEarlyEPCallbacks)
     C(MPM, Level);
 
   // Create a function that performs CFI checks for cross-DSO calls with targets
   // in the current module.
   MPM.addPass(CrossDSOCFIPass());
 
   if (Level == OptimizationLevel::O0) {