(Thrift Field Masker Pt1) Remove redundant thrift files (#6310)

Motivation:

While adding test cases for thrift, I found it inconvenient to update
thrift messages for each module (thrift0.9, thrift0.12, and thrift
0.13).
When diffing each file, the only difference I found for thrift0.9 was
`i8` was used instead of `byte`.

I propose that thrift0.13 IDL definitions are used across all versions.
To accomodate thrift0.9, a new `thrift9ify` task is added.

Modifications:

- Removed thrift IDL definitions for thrift0.9, thrift0.12.

Result:

- It is easier to define thrift messages for tests

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Author: jrhee17

thrift/thrift0.12/build.gradle

@@ -46,6 +46,7 @@ tasks.processTestResources.from "${rootProject.projectDir}/thrift/thrift0.13/src
 def thriftFullVersion = libs.thrift012.get().versionConstraint.requiredVersion
 ext {
     thriftVersion = thriftFullVersion.substring(0, thriftFullVersion.lastIndexOf('.'))
+    testThriftSrcDirs = ["${rootProject.projectDir}/thrift/thrift0.13/src/test/thrift"]
 }
 
 // Disable checkstyle because it's checked by ':thrift0.13'.