Cleanup test cases for file input

[jsirianni]

Description of Changes

porting test changes open-telemetry/opentelemetry-log-collection#165

Please check that the PR fulfills these requirements

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• Add a changelog entry (for non-trivial bug fixes / features)
• CI passes

[djaglowski]

Log Files	Logs / Second	CPU Avg (%)	CPU Avg Δ (%)	Memory Avg (MB)	Memory Avg Δ (MB)
1	1000	1.4482398	-0.051778555	128.58769	+1.8954773
1	5000	5.086408	+0.3621359	137.81451	-2.4224243
1	10000	10.206966	-0.8453455	145.48923	+1.8407898
1	50000	49.82828	+4.5540123	173.4441	+1.5743561
1	100000	101.6831	+9.558105	238.42578	+0.6577301
10	100	1.8965814	+0.103394985	133.18683	-0.312088
10	500	6.0691338	+0.7070408	142.20905	+1.8635406
10	1000	11.034619	-0.94857216	148.31142	-0.23344421
10	5000	55.983425	+0.22272873	180.42712	+2.3810577
10	10000	107.49732	+8.259186	226.18117	-8.544998

[codecov]

Codecov Report

Merging #343 (822f70c) into master (baa994e) will decrease coverage by 0.08%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #343      +/-   ##
==========================================
- Coverage   69.68%   69.60%   -0.08%     
==========================================
  Files         123      123              
  Lines        6491     6491              
==========================================
- Hits         4523     4518       -5     
- Misses       1492     1496       +4     
- Partials      476      477       +1     

Impacted Files	Coverage Δ
operator/builtin/input/tcp/tcp.go	69.30% <0.00%> (-4.39%)	⬇️

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