[functorch] test: try using reference_inputs in vmap tests (#91355)
Ref https://github.com/pytorch/functorch/issues/1090
Timings:
`test_vmap_exhaustive`
After PR
```
== 1168 passed, 55 skipped, 2353 deselected, 153 xfailed in 195.07s (0:03:15) ==
```
Before PR
```
== 1134 passed, 55 skipped, 2316 deselected, 150 xfailed in 77.18s (0:01:17) ==
```
`test_op_has_batch_rule`
After PR
```
== 988 passed, 57 skipped, 2353 deselected, 331 xfailed in 144.70s (0:02:24) ==
```
Before PR
```
== 969 passed, 57 skipped, 2316 deselected, 313 xfailed in 65.86s (0:01:05) ==
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/91355
Approved by: https://github.com/zou3519
