Improve building with test coverage information

[durgakiran]

Description

Closes #2102.

Added new task to start ferretdb proxy server with coverage build. The coverage will be stored in directory GOCOVERDIR: covdatafiles at the root level.

env-ferretdb-build:
    desc: "Run ferretdb proxy"
    cmds:
      - rm -rf covdatafiles
      - mkdir covdatafiles
      - go build -cover -v  -o=bin/ferretdb{{exeExt}} -race=true -coverpkg=./... ./cmd/ferretdb
      - ./bin/ferretdb{{exeExt}} --log-level="warn"

Updated task test-integration-pg: so that it runs the test cases against ferretdb proxy server, and generates integration-pg.txt as it used to be. To generate I have used the command ./bin/ferretdb --append-coverage-meta to emit coverage data into given directory (GOCOVERDIR: covdatafiles) and then go tooling to generate text report.

Note: task security is failing, asking for some minor updates. But I didn't work on changing anything here.

Readiness checklist

• I added/updated unit tests (and they pass).
• I added/updated integration/compatibility tests (and they pass).
• I added/updated comments and checked rendering.
• I made spot refactorings.
• I updated user documentation.
• I ran task all, and it passed.
• I ensured that PR title is good enough for the changelog.
• (for maintainers only) I set Reviewers (@FerretDB/core), Labels, Project and project's Sprint fields.
• I marked all done items in this checklist.

[CLAassistant]

All committers have signed the CLA.

[AlekSi]

@durgakiran please click the CLA button in the message above

[codecov]

Codecov Report

Merging #3059 (4b2ae36) into main (f1f284e) will decrease coverage by 2.50%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3059      +/-   ##
==========================================
- Coverage   75.17%   72.67%   -2.50%     
==========================================
  Files         396      396              
  Lines       22210    22210              
==========================================
- Hits        16696    16142     -554     
- Misses       4526     5025     +499     
- Partials      988     1043      +55     

Files Changed	Coverage Δ
build/version/version.go	67.64% <ø> (ø)

... and 57 files with indirect coverage changes

Flag	Coverage Δ
hana	?
integration	68.74% <ø> (-2.77%)	⬇️
mongodb	5.30% <ø> (ø)
pg	60.43% <ø> (-4.79%)	⬇️
shard-1	56.67% <ø> (-0.03%)	⬇️
shard-2	29.97% <ø> (-24.15%)	⬇️
shard-3	55.28% <ø> (-0.20%)	⬇️
sqlite	37.37% <ø> (+2.02%)	⬆️
unit	24.68% <ø> (-0.05%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

[chilagrow]

task security is failing, asking for some minor updates. But I didn't work on changing anything here.

Try using go1.20.6 version, that patch has fixed some vulnerabilities 🤗

$ go version
go version go1.20.6 linux/amd64

[AlekSi]

I did some small final cleanups, the PR should be merged soon. Thank you!

[rumyantseva]

LGTM!