Update Python labels and remove unnecessary ones (#15893)

This PR leverages some of the new labels we have for organizing our issues and removes labels that aren't really used at the moment. If reviewers feel strongly I can keep the ci label, but AFAICT that doesn't really get used for anything at the moment and we'll benefit more from leveraging future labels to help direct tasks to the build/infra team vs cudf devs.

Authors:
  - Vyas Ramasubramani (https://github.com/vyasr)

Approvers:
  - Bradley Dice (https://github.com/bdice)
  - GALI PREM SAGAR (https://github.com/galipremsagar)

URL: #15893

.github/labeler.yml

@@ -1,9 +1,19 @@
 # Documentation for config - https://github.com/actions/labeler#common-examples
 
-cuDF (Python):
+Python:
   - 'python/**'
   - 'notebooks/**'
 
+cudf.pandas:
+  - 'python/cudf/cudf/pandas/**'
+  - 'python/cudf/cudf_pandas_tests/**'
+
+cudf.polars:
+  - 'python/cudf_polars/**'
+
+pylibcudf:
+  - 'python/cudf/cudf/_lib/pylibcudf/**'
+
 libcudf:
   - 'cpp/**'
 
@@ -12,11 +22,5 @@ CMake:
   - '**/cmake/**'
   - '**/*.cmake'
 
-cuDF (Java):
+Java:
   - 'java/**'
-
-ci:
-  - 'ci/**'
-
-conda:
-  - 'conda/**'