THREESCALE-12434: Migrate from protected attributes to strong parameters - Part 3

[mayorova]

What this PR does / why we need it:

This is part 3 (final) of the migration from protected attributes to strong parameters. See also:

• part 1: THREESCALE-12434: Migrate from protected attributes to strong parameters - Part 1 #4248
• part 2: THREESCALE-12434: Migrate from protected attributes to strong parameters - Part 2 #4249

Protected attributes is an old Rails feature which was deprecated a long time ago. We were using protected_attributes_continued gem to keep it working, but now it's also discontinued and does not support Rails 7+, so it's a blocker for upgrading to Rails 7.2 for us.

This part clears up all the remaining references to protected attributes, and removes the protected_attributes_continued gem.

Which issue(s) this PR fixes

https://redhat.atlassian.net/browse/THREESCALE-12434

Verification steps

All tests should pass, and all features should work as before.

Special notes for your reviewer:

[qltysh]

❌ 7 blocking issues (7 total)

Tool	Category	Rule	Count
rubocop	Lint	Class has too many lines. [206/200]	5	❌
rubocop	Lint	Block has too many lines. [118/25]	1	❌
rubocop	Lint	Assignment Branch Condition size for create\_a\_complete\_provider is too high. [<16, 154, 1> 154.8/20]	1	❌