cloudapi: lint fixes + just use crypto/rand

[mstoykov]

What?

Some leftover lint fixes and just move to crypto/rand for the idempotency token.

Part of #769

Why?

Fixes lint issues

Checklist

• I have performed a self-review of my code.
• I have added tests for my changes.
• I have run linter locally (make lint) and all checks pass.
• I have run tests locally (make tests) and all tests pass.
• I have commented on my code, particularly in hard-to-understand areas.

Related PR(s)/Issue(s)

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.56%. Comparing base (47c5bb0) to head (934d258).

❗ Current head 934d258 differs from pull request most recent head 3bb5dc2. Consider uploading reports for the commit 3bb5dc2 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3627      +/-   ##
==========================================
- Coverage   73.57%   73.56%   -0.02%     
==========================================
  Files         277      277              
  Lines       20244    20243       -1     
==========================================
- Hits        14895    14892       -3     
- Misses       4401     4403       +2     
  Partials      948      948              

Flag	Coverage Δ
macos	?
ubuntu	73.52% <ø> (-0.01%)	⬇️
windows	73.42% <ø> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.