Remove deprecated method parameter from merge and join.

[bdice]

This PR removes the deprecated method parameter from DataFrame.merge and DataFrame.join. This resolves #9353 and follows up on #9291.

[galipremsagar]

rerun tests

[galipremsagar]

rerun tests

[vyasr]

@bdice looks like there are a couple more tests that need fixing here.

[codecov]

Codecov Report

Merging #9944 (b61ad03) into branch-22.02 (967a333) will decrease coverage by 0.07%.
The diff coverage is n/a.

@@               Coverage Diff                @@
##           branch-22.02    #9944      +/-   ##
================================================
- Coverage         10.49%   10.41%   -0.08%     
================================================
  Files               119      119              
  Lines             20305    20494     +189     
================================================
+ Hits               2130     2134       +4     
- Misses            18175    18360     +185     

Impacted Files	Coverage Δ
python/custreamz/custreamz/kafka.py	29.16% <0.00%> (-0.63%)	⬇️
python/dask_cudf/dask_cudf/sorting.py	92.30% <0.00%> (-0.61%)	⬇️
python/cudf/cudf/__init__.py	0.00% <0.00%> (ø)
python/cudf/cudf/core/frame.py	0.00% <0.00%> (ø)
python/cudf/cudf/core/index.py	0.00% <0.00%> (ø)
python/cudf/cudf/io/parquet.py	0.00% <0.00%> (ø)
python/cudf/cudf/core/series.py	0.00% <0.00%> (ø)
python/cudf/cudf/utils/utils.py	0.00% <0.00%> (ø)
python/cudf/cudf/utils/dtypes.py	0.00% <0.00%> (ø)
python/cudf/cudf/utils/ioutils.py	0.00% <0.00%> (ø)
... and 20 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b8c4816...b61ad03. Read the comment docs.

[bdice]

@gpucibot merge

[bdice]

@gpucibot merge