fix: resolve blank repo metadata

[hugorut]

Resolves issue where repo metadata is blank for infracost comment. This fixes a regression that was introduced with the ContextValues concurrency fix. Prior to the concurrency fix RunContext Values was returning the value of the underlying map and not a copy for it. So setting ctxValues['repoMetadata'] actually altered the RunContext Values. Hence why the old code which set the key before creating a clone actually worked. The old code with comments for better understanding:

// This line actually alters ctx.Values as well as the local variable.
ctxValues["repoMetadata"] = metadata

if ctx.IsInfracostComment() {
	ctxValues = make(map[string]interface{}, len(ctxValues))
        // now ctx.ctx.GetContextValues returns the altered map so the clone contains the "repoMetadata" key.
	for k, v := range ctx.GetContextValues() {
		ctxValues[k] = v
	}
	ctxValues["command"] = "comment"
}

once this was changed to return a map copy ctxValues this meant:

// This line only modified the local variable.
ctxValues["repoMetadata"] = metadata

if ctx.IsInfracostComment() {
	ctxValues = make(map[string]interface{}, len(ctxValues))
	// Then Values returns the unaltered ctx values (the correct behaviour).
	for k, v := range ctx.ContextValues.Values() {
		ctxValues[k] = v
	}
	ctxValues["command"] = "comment"
}

So repoMetadata was removed.

This fix removes the unecessary ctxValues copy (as it is already a local copy) and instead just sets the command to be the correct string.