PERF: fix clean_index_list perf

[jreback]

closes #16285

In [1]: np.random.seed(1234)

In [2]: import pandas as pd
   ...: from numpy import random
   ...: dct = dict(zip(range(1000), random.randint(1000, size=1000)))
   ...: keys = random.randint(1000, size=1000000).tolist()
   ...: %timeit [dct[k] for k in keys]
   ...: sdct = pd.Series(dct)
   ...: %timeit sdct[keys]

0.19.2

76.7 ms ± 1.12 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)
568 ms ± 5.07 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)

0.20.1

85.9 ms ± 2.58 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)
691 ms ± 20.4 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)

0.20.2

90.5 ms ± 1.09 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)
282 ms ± 5.11 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)

[codecov]

Codecov Report

Merging #16295 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #16295      +/-   ##
==========================================
- Coverage   90.39%   90.37%   -0.02%     
==========================================
  Files         161      161              
  Lines       50863    50863              
==========================================
- Hits        45977    45969       -8     
- Misses       4886     4894       +8

Flag	Coverage Δ
#multiple	88.16% <ø> (ø)	⬆️
#single	40.33% <ø> (-0.1%)	⬇️

Impacted Files	Coverage Δ
pandas/core/indexes/base.py	95.75% <ø> (ø)	⬆️
pandas/io/gbq.py	25% <0%> (-58.34%)	⬇️
pandas/core/frame.py	97.59% <0%> (-0.1%)	⬇️
pandas/io/clipboard/clipboard.py
pandas/io/clipboards.py	100% <0%> (ø)
pandas/core/common.py	91.03% <0%> (+0.34%)	⬆️

---

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[codecov]

Codecov Report

Merging #16295 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #16295      +/-   ##
==========================================
- Coverage   90.39%   90.37%   -0.02%     
==========================================
  Files         161      161              
  Lines       50863    50863              
==========================================
- Hits        45977    45969       -8     
- Misses       4886     4894       +8

Flag	Coverage Δ
#multiple	88.16% <ø> (ø)	⬆️
#single	40.33% <ø> (-0.1%)	⬇️

Impacted Files	Coverage Δ
pandas/core/indexes/base.py	95.75% <ø> (ø)	⬆️
pandas/io/gbq.py	25% <0%> (-58.34%)	⬇️
pandas/core/frame.py	97.59% <0%> (-0.1%)	⬇️
pandas/io/clipboard/clipboard.py
pandas/io/clipboards.py	100% <0%> (ø)
pandas/core/common.py	91.03% <0%> (+0.34%)	⬆️

---

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 4bed864...b8fb546. Read the comment docs.