Update upmerge workflow to ignore bicepconfig.json changes

[sk593]

Bug information

Steps to reproduce (required)

This is a bug happening in the release-samples.sh workflow that is caused by the upmerge samples workflow. The bicepconfig.json in the previous release branch (i.e. v0.38) has a release-specific tag as opposed to the latest tag that is in edge. When we upmerge the edge branch, we don't want the release specific tag to overwrite the latest tag in edge.

Observed behavior (required)

The release-specific tag is overwriting the latest tag in the bicepconfig.json in edge when we run the upmerge samples workflow. See this upmerge PR for an example: https://github.com/radius-project/samples/pull/1864/files#diff-cd3c8fe9d6a9f8debd89f78fa0f9a9b4c38d02fff5538d7bcb0eaf7fe857a0b4

When we run the release samples workflow, we check for the latest tag in the bicepconfig.json to update. If this tag is not present and has been overwritten by a release-specific tag, i.e. 0.38, the bicepconfig.json won't get updated appropiately. See here for the part where we update the bicepconfig.json:

samples/.github/scripts/release-samples.sh

Line 44 in c2df310

BICEPCONFIG_RADIUS_STRING_REPLACEMENT="br:biceptypes.azurecr.io/radius:${CHANNEL}"

Desired behavior (required)

We want to avoid overwriting the edge version of the bicepconfig.json when upmerging samples.

Workaround (optional)

System information

rad Version (required)

Operating system (required)

Additional context

AB#13445