Fix Android CI Pipeline code coverage failure (#21504)
### Description
<!-- Describe your changes. -->
Current failure is due to a version mismatch.
Use llvm-cov from the Android NDK instead of the system gcov so that the
version is correct.
Also comment out publishing to the Azure dashboard to simplify the
setup. The CI prints out the stats for review by developers.
### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
Fix CI pipeline
