updated rx client to remove cache busting

[agravell047]

Summary

We were seeing an error when calling this with nil keys:
Common::Collection.bust([cache_key('getactiverx'), cache_key('gethistoryrx')])

More investigation is needed but for the time being this works.

Related issue(s)

No ticket related, investigating urgent issue

Testing done

• Tested locally

Screenshots

None

What areas of the site does it impact?

MHV/mobile medications apps

Acceptance criteria

• I fixed|updated|added unit tests and integration tests for each feature (if applicable).
• No error nor warning in the console.
• Events are being sent to the appropriate logging solution
• Documentation has been updated (link to documentation)
• No sensitive information (i.e. PII/credentials/internal URLs/etc.) is captured in logging, hardcoded, or specs
• Feature/bug has a monitor built into Datadog or Grafana (if applicable)
• If app impacted requires authentication, did you login to a local build and verify all authenticated routes work as expected
• I added a screenshot of the developed feature

Requested Feedback

(OPTIONAL)What should the reviewers know in addition to the above. Is there anything specific you wish the reviewer to assist with. Do you have any concerns with this PR, why?