Fix umask=false for images without a shell entrypoint

[PigeonF]

While checking #1297 I got an error with (essentially) the following CI file

---
build:
  image:
    name: gcr.io/kaniko-project/executor:v1.23.0-debug
    entrypoint: [""]
  script:
    - ls

failed for me with

$ gitlab-ci-local --umask=false
Using fallback git commit data
Unable to retrieve default remote branch, falling back to `main`.
Using fallback git remote data
parsing and downloads finished in 49 ms.
json schema validated in 206 ms
build starting gcr.io/kaniko-project/executor:v1.23.0-debug (test)
Error: Command failed with exit code 1: docker run --rm gcr.io/kaniko-project/executor:v1.23.0-debug sh -c echo "$(id -u):$(id -g)"
Error: unknown command "sh" for "executor"
Run 'executor --help' for usage.
    at makeError (/nix/store/c89rzb02w6k156nzfxdi3rkmlngg4ma4-gitlab-ci-local-4.52.1/lib/node_modules/gitlab-ci-local/node_modules/execa/lib/error.js:60:11)
    at handlePromise (/nix/store/c89rzb02w6k156nzfxdi3rkmlngg4ma4-gitlab-ci-local-4.52.1/lib/node_modules/gitlab-ci-local/node_modules/execa/index.js:118:26)
    at processTicksAndRejections (node:internal/process/task_queues:95:5)
    at Job.start (/nix/store/c89rzb02w6k156nzfxdi3rkmlngg4ma4-gitlab-ci-local-4.52.1/lib/node_modules/gitlab-ci-local/src/job.ts:494:34)
    at /nix/store/c89rzb02w6k156nzfxdi3rkmlngg4ma4-gitlab-ci-local-4.52.1/lib/node_modules/gitlab-ci-local/node_modules/p-map/index.js:57:22

The fix is to explicitly set the entrypoint to sh when spawning the image to check the UID and GID of the container, so that the UID and GID of containers that have their entrypoint set to something other than a shell can still be retrieved.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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