fix: Recreate Synthetics resources on account ID change

[mbazhlekova]

Description

This PR forces a new Synthetics resource if Account ID is changed

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

Please delete options that are not relevant.

• My commit message follows conventional commits
• My code is formatted to Go standards
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes. Go here for instructions on running tests locally.

How to test this change?

1. Create a Synthetics monitor in one account
2. Switch to a different account and change the account ID for the monitor
3. Apply again

The Synthetics monitor should be deleted from the original account and recreated in the new account.

[codecov-commenter]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (0db566f) 33.83% compared to head (7904555) 35.18%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
newrelic/resource_newrelic_api_access_key.go	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2518      +/-   ##
==========================================
+ Coverage   33.83%   35.18%   +1.35%     
==========================================
  Files          91       91              
  Lines       24924    24927       +3     
==========================================
+ Hits         8432     8771     +339     
+ Misses      16336    15954     -382     
- Partials      156      202      +46     

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