when loading code for internal purposes, load stdlib files directly(#53326)
This bypasses DEPOT_PATH, LOAD_PATH, and stale checks when loading
known stdlib code for known purposes from known locations, specifically
to avoid the problem that I cannot fix my tools because I have used my
tools to break my tools.
This helps avoid the situation that the user can break important Pkg,
REPL, Socket or similar features simply because they chose to remove
`@stdlib` from their environment. For example, if you make an edit to
REPL, then this will trigger recompilation and load the edited version:
```
$ ./julia -e 'using REPL' -iq
┌ Info: Precompiling REPL [3fa0cd96-eef1-5676-8a61-b3b8758bbffb] (cache misses: include_dependency fsize change (2), invalid header (10), mismatched flags (1))
└ @ Base loading.jl:2643
julia>
```
But this will load the version that shipped with Julia, regardless of
the state of the cache or the source code (unless you delete the cache
files):
```
$ ./julia -iq
julia>
```
Fixes #53365