Don't include any files with extension .kotlin_metadata in R8 jars

The .kotlin_metadata files from the internalized Kotlin code (the Kotlin
metadata library and dependencies) are not required at runtime.

Bug: 136636007
Change-Id: Id84eb51dbe9c2fad7428d0d327fd3a82e96be832

build.gradle

diff --git a/build.gradle b/build.gradle
index 9ad1eb3..a9621d8 100644
--- a/build.gradle
+++ b/build.gradle
@@ -715,6 +715,7 @@
     from repackageDeps.outputs.files
     configureRelocations(it)
     exclude "META-INF/*.kotlin_module"
+    exclude "**/*.kotlin_metadata"
 }
 
 task r8WithRelocatedDeps11(type: ShadowJar) {
@@ -729,6 +730,7 @@
     from repackageDeps.outputs.files
     configureRelocations(it)
     exclude "META-INF/*.kotlin_module"
+    exclude "**/*.kotlin_metadata"
 }
 
 task r8WithoutDeps(type: ShadowJar) {
@@ -759,6 +761,7 @@
         from sourceSets.main.output
     }
     exclude "META-INF/*.kotlin_module"
+    exclude "**/*.kotlin_metadata"
 }
 
 task R8NoManifestNoDeps(type: ShadowJar) {
@@ -783,6 +786,7 @@
         from sourceSets.main.output
     }
     exclude "META-INF/*.kotlin_module"
+    exclude "**/*.kotlin_metadata"
 }
 
 task D8(type: ShadowJar) {