Do not add _platform suffix to non-apex variation

This commit renames `_platform` suffix to `` (empty string) so that
non-apex variations are not renamed to `_core_shared_platform` or
`_vendor_shared_platform`.

This commit makes sure that `_core_shared` and `_vendor_shared` is
always under `$OUT_DIR/soong` regardless the usages from apex modules.
Furthermore, this avoids the confusing stale lsdump files (e.g. both
`_core_shared` and `_core_shared_platform exist) while creating
reference ABI dumps for VNDK ABI checks.

Bug: 121986692
Test: lunch aosp_arm64-userdebug; make  # no more _platform variants.
Change-Id: Ic02a60ac45f982580349661c22331d114617fd92

android/apex.go

@@ -122,15 +122,13 @@ func (m *ApexModuleBase) IsInstallableToApex() bool {
 
 func (m *ApexModuleBase) CreateApexVariations(mctx BottomUpMutatorContext) []blueprint.Module {
 	if len(m.apexVariations) > 0 {
-		// The original module is mutated into "platform" variation.
-		variations := []string{"platform"}
-		for _, a := range m.apexVariations {
-			variations = append(variations, a)
-		}
+		variations := []string{""} // Original variation for platform
+		variations = append(variations, m.apexVariations...)
+
 		modules := mctx.CreateVariations(variations...)
 		for i, m := range modules {
 			if i == 0 {
-				continue // platform
+				continue
 			}
 			m.(ApexModule).setApexName(variations[i])
 		}