[rocm-libraries] ROCm/rocm-libraries#7743 (commit 15ef85c)

[CK] Extract Jenkinsfile helpers into vars/ck.groovy shared
 library (#7743)

## Motivation
The CK Jenkinsfile is a 2,215-line monolith mixing helper function
definitions with pipeline stage declarations. This makes it difficult to
review, modify, or extend CI stages without wading through unrelated
infrastructure code.

## Technical Details
Extract all helper functions from the Jenkinsfile into vars/ck.groovy,
loaded at runtime via ck = load "vars/ck.groovy" in the first stage. The
Jenkinsfile is reduced from 2,215 lines to 810 lines containing only the
pipeline structure.

- 36 helper functions moved to ck.groovy with no logic changes
- 10 new stage-wrapper functions (runBuildCKAndTests,
runTileEngineGemmTests, runClangFormat, etc.) extract inline
environment{}/steps{} business logic from stages, eliminating the
MethodTooLargeException caused by CPS-transformed shell strings
exceeding the JVM 64KB bytecode limit
- All ck. method calls in steps{} blocks wrapped in script{} as required
by Jenkins Declarative Pipeline
- rocmnode() remains in the Jenkinsfile (needed for agent{} labels
before ck is loaded)
- CRON_SETTINGS / POLL_SPEC remain in the Jenkinsfile (triggers{}
evaluates at parse time before any workspace is available)
- No stage names changed

## Test Plan
- Jenkinsfile validated against the Jenkins Pipeline Linter
(/pipeline-model-converter/validate)
- All 35 shared helper functions diffed line-by-line against develop to
verify no regressions
- Merge from develop incorporated and verified (gfx1250 stage, ROCm 7.13
default, cmake_build updates)

## Test Result
- Linter: passes
- Function diff vs develop: all 35 functions match exactly
- Awaiting Jenkins run to confirm end-to-end stage execution

## Submission Checklist

- [ x ] Look over the contributing guidelines at
https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.

Author: brockhargreaves-amd