CRM: Clean up small bits of unused code

[tbradsha]

While digging into the issue now documented at https://github.com/Automattic/zero-bs-crm/issues/3542#issuecomment-2810534336, I ran across several small bits of code that are no longer used, so this PR cleans them up.

Proposed changes:

This chops the following functions

• zbsCustomer_companyDropdown()
• ZeroBSCRM::setup_environment()
• zeroBSCRM_getContactOrCustomer()
• zeroBSCRM_getCompanyOrOrg()
• zeroBSCRM_getCompanyOrOrgPlural()
• zeroBSCRM_exposePID()

It also does some minor linting and chops some old comments.

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

Does this pull request change what data or activity we track or use?

Testing instructions:

Make sure the deleted functions aren't used in the monorepo, the main extensions repo, or the Mail Campaigns repo.

[github-actions]

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[jp-launch-control]

Code Coverage Summary

Coverage changed in 4 files.

File	Coverage	Δ%	Δ Uncovered
projects/plugins/crm/includes/jpcrm-language.php	0/14 (0.00%)	0.00%	1 ❤️‍🩹
projects/plugins/crm/includes/ZeroBSCRM.Core.php	0/982 (0.00%)	0.00%	-2 💚
projects/plugins/crm/includes/ZeroBSCRM.Forms.php	0/149 (0.00%)	0.00%	-2 💚
projects/plugins/crm/includes/ZeroBSCRM.MetaBoxes3.Contacts.php	0/838 (0.00%)	0.00%	-9 💚

Full summary · PHP report

[coder-karen]

Confirmed none of the repositories use any of the removed functions.