Disable custom_rr_abi.swift
Failing in Swift Incremental RA - macOS - Apple Silicon
https://ci.swift.org/job/oss-swift-incremental-RA-macos-apple-silicon/2266/
```
[ RUN ] CustomRRABI.retain
stderr>>> CRASHED: SIGSEGV
the test crashed unexpectedly
[ FAIL ] CustomRRABI.retain
CustomRRABI: Some tests failed, aborting
UXPASS: []
FAIL: ["retain"]
SKIP: []
To debug, run:
$ /Users/ec2-user/jenkins/workspace/oss-swift-incremental-RA-macos-apple-silicon/build/buildbot_incremental/swift-macosx-arm64/test-macosx-arm64/Runtime/Output/custom_rr_abi.swift.tmp/a.out --stdlib-unittest-in-process --stdlib-unittest-filter "retain"
```
rdar://102912772
