ci: Add proper CoreCLR support, remove Mono from trunk and update architecture setup in CI

[michalChrobot]

Purpose of this PR

This PR resolves few pending CI issues that we have which is:

1. In trunk x64 architecture for macOS was completely removed and it's now ARM64 only so I addressed this here by specifying architecture per each supported platform that we used (issue was that without that param specified the trunk job tried to use x64 arch which is now nonexistent there). For mobile devices there is a split in build platform architecture and actual mobile platform architecture
2. I added CoreCLR support for players and worth noting is that is mainly for 6000.7 (coreclr is in preview and you need to specify that you want to use coreclr player) while on trunk the default editor is already coreclr-based + mono is removed so I addressed this here
3. I also added full configuration to job title so even if we run package tests we know which scripting backend is being used (on trunk it's coreclr while on previous editors is mono)
4. I changed NetcodeConfig in minimalproject to remove automated bootstrapping as otherwise we get warning --> When running minimalproject I get "[UnifiedBootstrap] Auto-bootstrap is enabled!!! This will break the POC!"

Jira ticket

https://jira.unity3d.com/browse/MTT-16251

Documentation

N/A

Testing & QA (How your changes can be verified during release Playtest)

I will run full set of jobs (weekly) to check if everything works

[u-pr]

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[u-pr]

💡 Harness Review

The CI templates add CoreCLR player coverage and explicit Editor architectures, but a scheduled mobile build still has an architecture mismatch.

_{Reviewed commit 8f9e129}

_{🤖 Helpful? 👍/👎}

[u-pr]

The iOS build loops over validation_editors.all, which includes trunk, and the nightly trunk mobile-test group depends on that build. This value makes the downloader request a macOS x64 trunk Editor, but trunk no longer provides one, so the iOS build and its test cannot start. Use the ARM64 macOS build image and architecture: arm64; keep target_architecture: arm64 for the player.

_{🤖 Helpful? 👍/👎}

[codecov-github-com]

Codecov Report

All modified and coverable lines are covered by tests ✅

@@              Coverage Diff               @@
##           develop-3.x.x    #4177   +/-   ##
==============================================
  Coverage          78.19%   78.19%           
==============================================
  Files                153      153           
  Lines              26272    26272           
==============================================
  Hits               20544    20544           
  Misses              5728     5728           

Flag	Coverage Δ
NGOv2_project_testproject_ubuntu	76.65% <ø> (ø)

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Components	Coverage Δ
com.unity.netcode.gameobjects	78.19% <ø> (ø)

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