gh-145098: Use macos-26-intel instead of macos-15-intel

[hugovk]

This reverts commit cb76ab3, actions/runner-images#13882 (comment) should be fixed now.

• Issue: CI: move Apple Silicon macOS workflows to macos-26 (Tahoe) #145098

[hugovk]

We first need to skip the tkinter timout on macOS 26 Intel:

• test_wm_iconbitmap() timeout after 10 min on "macOS / build and test (macos-26-intel)" CI #146531
• gh-146531: Skip hanging wm iconbitmap test on macOS 26 Intel #148032

[hugovk]

Let's run this in main for a little before backporting.

Will also need the tkinter timeout backporting, or wait for Ned to look into fixing it after PyCon US.

[hugovk]

It's been a few months, let's backport. Will try without the tkinter test skip at first, but will also backport that if needed.

[miss-islington-app]

Thanks @hugovk for the PR 🌮🎉.. I'm working now to backport this PR to: 3.15.
🐍🍒⛏🤖

[bedevere-app]

GH-153179 is a backport of this pull request to the 3.15 branch.

[miss-islington-app]

Thanks @hugovk for the PR 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖

[bedevere-app]

GH-153181 is a backport of this pull request to the 3.14 branch.

[miss-islington-app]

Thanks @hugovk for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13.
🐍🍒⛏🤖

[miss-islington-app]

Sorry, @hugovk, I could not cleanly backport this to 3.13 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 517d3d2c10c7e6214d1785cf27f768809910e52c 3.13

[bedevere-app]

GH-153185 is a backport of this pull request to the 3.13 branch.

[miss-islington-app]

Thanks @hugovk for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖

[miss-islington-app]

Sorry, @hugovk, I could not cleanly backport this to 3.12 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 517d3d2c10c7e6214d1785cf27f768809910e52c 3.12

[bedevere-app]

GH-153186 is a backport of this pull request to the 3.12 branch.