* OPIK-980: Embed opik-sandbox-executor-python image during builds

* [OPIK-980] update workflow and dockerfile for opik-python-backend (#1296)

* update workflow and dockerfile for opik-python-backend

* update envvars

* remove uneeded file

* adjustments for optional tar.gz image file

* Rev3: adding echo and comments

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Co-authored-by: Liya Katz <liyak@comet.com>