Changes

fix(tikv): resolving the test issue for unit-test-coverage job (#4037)

- Add --test-threads to increase the test concurrency.
- Resolving the capacity issue by using the volumeClaimTemplate of the
ephemeral volume to create independent storage space for the Pod,
avoiding restrictions imposed by the node's ephemeral-storage resource.
- filter out the data of dependencies to reduce the size of the
generated lcov.info file to upload to codecov.io successfully.

---------

Co-authored-by: wuhuizuo <wuhuizuo@126.com>
 (commit: 2e8fe53)