fix fetch-submodules.sh for older git

[dhalbert]

#8070 did not work properly with older versions of git that could not do partial clones (before git 2.36). I tested this with git 2.30.1 on several ports, starting with no submodules each time. I was able to simplify the older shallow-depth commands a bit.

Thanks @jposada202020 who found the initial problem.

If you has an older version of git (before 2.36) and are interested in testing, you could try this. The simplest way is probably just replacing tools/fetch-submodules.sh from main with the new version here.

[RetiredWizard]

I'm running ubuntu 22.04 & git 2.34.1. I was seeing the issue reported by @jposada202020 but after replacing tools/fetch-submodules.sh with this version I've run the new fetch-port-submodules and built a board on atmel-samd, broadcom, espressif, mimxrt10xx, nrf, raspberrypi, silabs and stm without any issue.

[jposada202020]

Looks good to me.
Two Tests:

1. Machine test ubuntu 22.04 with Git 2.40.1 ---- Worked fetching port submodules
2. Machine test ubuntu 22.04 with git 2.34.1 --- Worked fetching port submodules

[jepler]

Approving based on others testing