test: fix deprecations and warnings reported by phpunit 13

[mislavjakopovic]

Q	A
Branch?	5.0
Tickets	none
PRs	Preparation for #8537
License	MIT
Doc PR	n/a

PHPUnit 13 makes three things in our tests a problem:

• with() on a test double (stub, mock) that never calls expects() is deprecated (Deprecate using with*() on test stubs sebastianbergmann/phpunit#6510, PHPUnit 12.5.11) and PHPUnit 13.0 removed the with*() methods from the InvocationStubber interface - the runtime deprecation announces the removal in PHPUnit 14. PHPUnit 13 also emits a "No expectations were configured for the mock object" notice for such doubles ("No expectations were configured for the mock object ..." notice is emitted when with() is used without expects() sebastianbergmann/phpunit#6509).
• the any() matcher is deprecated (Deprecate any() matcher sebastianbergmann/phpunit#6461, soft in 12.5.5, hard in 13.0).
• comparing closures for equality with assertEquals() emits a warning since PHPUnit 13.2.0 (sebastianbergmann/phpunit@08aedf2, built on Expose detection of closure comparisons sebastianbergmann/comparator#163), which fails the graphql component job because its configuration has failOnWarning.

Currently PHPStan with PHPUnit 13 installed reports the 68 with() calls as calls to an undefined method on InvocationStubber.

This fix adjusts the test files concerned:

• doubles that only select a return value use willReturnMap() and are created with createStub();
• doubles where the call itself was the point keep with() and get a real expectation, expects($this->once()), or atLeastOnce() for the one shared in a setUp();
• expects($this->any()) becomes atLeastOnce();
• FieldsBuilderTest compares resolver closures with assertSame().

Additional clarification on why mocks were replaced with stubs

Without with() doubles carry no expectation, and as mentioned in problem #1 above PHPUnit 12.4+ flags every such createMock() object with "No expectations were configured for the mock object... use a test stub instead" (sebastianbergmann/phpunit#6509). Creating them as stubs does what the notice asks and keeps the notice count of every component suite unchanged; a stub is the same double minus expects(), which these objects never used. Following this change, variables were also renamed from $*Mock to $*Stub where their creation changed.

This pull request is part of several fixes needed to enable PHPUnit 13 support in PR #8537.