fix: scratch buffer initializing too early

[Dev380]

This is a daemon-only issue.
The scratch buffer is initialized very early
in the startup process. However, some minor
modes (such as flycheck-posframe-mode) and
other things that should run on every prog-mode
or elisp mode buffer won't get to set a hook and
have it run. This recreates the scratch buffer
the first time it's switched to to fix this.
For some reason, simply calling the major mode
hook for the scratch buffer after doom-after-init-hook
doesn't work.

For some reason, removing the check for the buffer name in the hook function (i.e. running it on the first buffer switch after doom-after-init-hook) also works, and the buffer switch hook runs automatically despite me not switching any buffers, but just doom-after-init-hook by itself doesn't work and I don't know why.

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• I searched the issue tracker and this hasn't been PRed before.
• My changes are not on the do-not-PR list for this project.
• My commits conform to the git conventions.