Clean up devfile exec package functions

[snowdrop-bot]

pkg/exec/devfile.go's ExecuteDevfileRunActionWithoutRestart(), ExecuteDevfileDebugActionWithoutRestart is ~95% similar to their non restart counterparts ExecuteDevfileRunAction, ExecuteDevfileDebugAction

To me it looks like a lot of redundant code and can be massively cleaned up by modifying the prev existing functions to handle non restarts.

Came across this when looking at ways to refactor kube/docker adapter's execDevfile() func in redhat-developer#3015

/area devfile
/kind cleanup

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redhat-developer#3518

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$upstream:3518$