[SPARK-38084][TESTS] Support `SKIP_PYTHON` and `SKIP_R` in `run-tests.py`
[SPARK-38084][TESTS] Support `SKIP_PYTHON` and `SKIP_R` in `run-tests.py`

### What changes were proposed in this pull request?

This PR aims to support `SKIP_PYTHON` and `SKIP_R` in `run-tests.py` like `SKIP_MIMA` and `SKIP_UNIDOC`.

### Why are the changes needed?

This is helpful to setup CIs.

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Manually.
```
SKIP_PYTHON=1 SKIP_R=1 dev/run-tests.py
```

Closes #35381 from dongjoon-hyun/SPARK-38084.

Authored-by: Dongjoon Hyun <6ff48b33cbb828151035af58a92f18a39f1d1036@apache.org>
Signed-off-by: Dongjoon Hyun <6ff48b33cbb828151035af58a92f18a39f1d1036@apache.org>
(cherry picked from commit 6347b9dc04576ef844a941460bb4a1814dc40dbb)
Signed-off-by: Dongjoon Hyun <6ff48b33cbb828151035af58a92f18a39f1d1036@apache.org>

milliman/spark,milliman/spark,milliman/spark,milliman/spark,milliman/spark,milliman/spark,milliman/spark