[SPARK-45483][CONNECT] Correct the function groups in connect.functions

### What changes were proposed in this pull request?
Correct the function groups in connect.functions

### Why are the changes needed?
to be consistent with apache@17da438

### Does this PR introduce _any_ user-facing change?
yes, will changes the scaladoc (when it is available)

### How was this patch tested?
ci

### Was this patch authored or co-authored using generative AI tooling?
no

Closes apache#43309 from zhengruifeng/connect_function_scaladoc.

Authored-by: Ruifeng Zheng <[email protected]>
Signed-off-by: Dongjoon Hyun <[email protected]>