CLN: tslibs imports and unused variables

[mroeschke]

• tests added / passed

• Remove unused imports, mostly Py_ssize_t, and variables

• Remove a block that is not hit after the DatetimeIndex.normalize performance upgrades PERF: Datetime/Timestamp.normalize for timezone naive datetimes #23634

[codecov]

Codecov Report

Merging #24401 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #24401   +/-   ##
=======================================
  Coverage    92.3%    92.3%           
=======================================
  Files         162      162           
  Lines       51875    51875           
=======================================
  Hits        47883    47883           
  Misses       3992     3992

Flag	Coverage Δ
#multiple	90.71% <ø> (ø)	⬆️
#single	42.99% <ø> (ø)	⬆️

---

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[codecov]

Codecov Report

Merging #24401 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #24401   +/-   ##
=======================================
  Coverage    92.3%    92.3%           
=======================================
  Files         162      162           
  Lines       51875    51875           
=======================================
  Hits        47883    47883           
  Misses       3992     3992

Flag	Coverage Δ
#multiple	90.71% <ø> (ø)	⬆️
#single	42.99% <ø> (ø)	⬆️

---

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 3e0358d...03f8c03. Read the comment docs.

[jreback]

thanks!