Batfish: disable parse reuse by default

[dhalperi]

When we added this feature, Batfish parsers were ridiculously slow and this
made a big difference. However, after we did a number of improvements to make
the parsers LL1 and in general use modes better and crappy ambiguous grammar
rules less, the parsers sped up dramatically. At this point, the reparsing is
often faster than deserializing prior results, and it uses less I/O.

Refs:

• Adding parse reuse in 2019: Reuse already-parsed files when safe to do so #3070
• grammar improvements, e.g., IOS: remove huge bgp_tail_null block for bgp #8268
• and this big blank line one: Parsers: remove BLANK_LINE, inline in F_Newline #6778

[batfish-bot]

This change is 

[progwriter]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @arifogel)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.14%. Comparing base (0edf444) to head (4fc5aa6).
Report is 46 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9214      +/-   ##
==========================================
- Coverage   78.16%   78.14%   -0.03%     
==========================================
  Files        3314     3314              
  Lines      170021   170021              
  Branches    20049    20049              
==========================================
- Hits       132899   132860      -39     
- Misses      37122    37161      +39     

Files with missing lines	Coverage Δ
...ish/src/main/java/org/batfish/config/Settings.java	85.43% <100.00%> (-0.33%)	⬇️

... and 4 files with indirect coverage changes