IPP Emails - remove hooks from constructors

[marcinbot]

Description

See base PR: #7249

We need to move the hooks from all class constructors to init_hooks and then call that method whenever the class is instantiated (or whenever we need the hooks to be attached, separately from instantiation).

The goal of this is to remove the side effects from constructors and allow us to instantiate classes freely.

Acceptance criteria

• Base the PR on Add DisallowHooksInConstructor sniff and migrate some classes to use it #7249 if not merged yet
• Remove the relevant exceptions from dev/phpcs/ruleset.xml
• Move the hooks to the new method and call them. Update the code and unit tests accordingly
• PHPCS should pass

CC @Automattic/pulsar

[vbelolapotkov]

@anu-rock @deepakpathania need your help with routing this one. On the one hand it's related to emails so probably falls into merchant comms (account lifecycle focus), on the other hand it's related to IPP styled receipts so might belong to payments processing focus. What are your thoughts? @marcinbot your input as an author is also welcome to find the best owner.

[anu-rock]

Right, curious to hear @marcinbot's thoughts on whether "emails" refer to just IPP's styled receipt emails or all emails.

[marcinbot]

@vbelolapotkov @anu-rock it appears that the IPP receipt is the only "email" that has this issue. I updated the title to reflect that. Hopefully it will help with the correct assignment.

[vbelolapotkov]

Ok, then routing it to @deepakpathania as the current owner of IPP work.