avoid fsync db in tests

[ucwong]

No description provided.

[codecov]

Codecov Report

Merging #1691 (29a26eb) into master (9c995d6) will decrease coverage by 0.02%.
Report is 6 commits behind head on master.
The diff coverage is 8.69%.

❗ Current head 29a26eb differs from pull request most recent head ca2ea9e. Consider uploading reports for the commit ca2ea9e to get more accurate results

@@            Coverage Diff             @@
##           master    #1691      +/-   ##
==========================================
- Coverage   52.55%   52.53%   -0.02%     
==========================================
  Files         481      481              
  Lines       60275    60284       +9     
==========================================
- Hits        31675    31671       -4     
- Misses      26191    26194       +3     
- Partials     2409     2419      +10     

Files Changed	Coverage Δ
core/rawdb/database.go	9.49% <0.00%> (ø)
core/rawdb/databases_64bit.go	0.00% <0.00%> (ø)
core/rawdb/schema.go	26.31% <0.00%> (-3.10%)	⬇️
ctxcdb/pebble/pebble.go	38.46% <28.57%> (-0.15%)	⬇️

... and 14 files with indirect coverage changes