Remove Database.Close

[AlekSi]

Description

Plus update documentation.

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), Milestone (Next), Labels, Project and project's Sprint fields.
• I marked all done items in this checklist.

[codecov]

Codecov Report

Merging #3327 (78be87e) into main (fb91ab1) will decrease coverage by 0.02%.
The diff coverage is 52.72%.

@@            Coverage Diff             @@
##             main    #3327      +/-   ##
==========================================
- Coverage   74.46%   74.44%   -0.02%     
==========================================
  Files         406      406              
  Lines       24189    24139      -50     
==========================================
- Hits        18013    17971      -42     
+ Misses       5115     5105      -10     
- Partials     1061     1063       +2     

Files Changed	Coverage
build/version/version.go	ø
ferretdb/ferretdb.go	ø
internal/backends/collection.go	ø
internal/backends/decorators/dummy/backend.go	0.00%
internal/backends/decorators/dummy/database.go	ø
internal/backends/decorators/oplog/backend.go	0.00%
internal/backends/decorators/oplog/database.go	ø
internal/backends/postgresql/backend.go	0.00%
internal/backends/postgresql/database.go	ø
internal/backends/sqlite/database.go	ø
... and 24 more

Flag	Coverage Δ
hana	?
integration	71.30% <56.86%> (-0.04%)	⬇️
mongodb	4.90% <0.00%> (+<0.01%)	⬆️
pg	60.75% <0.00%> (+0.11%)	⬆️
shard-1	55.32% <56.86%> (-0.08%)	⬇️
shard-2	54.34% <41.17%> (-0.05%)	⬇️
shard-3	54.22% <49.01%> (+0.05%)	⬆️
sqlite	55.89% <56.86%> (+0.08%)	⬆️
unit	23.96% <3.63%> (+0.04%)	⬆️

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

📢 Thoughts on this report? Let us know!.

[chilagrow]

The test for logout appears to be fixed for SQLite now too. Let's remove FailForSQLite 🤗

[chilagrow]

🚀