Remove deprecations for ConnectionHelper

[dmaicher]

Q	A
Type	improvement
BC Break	yes
Fixed issues	-

Summary

See #3956

Cleanup for the deprecated ConnectionHelper

[codecov-commenter]

Codecov Report

Merging #4059 into 3.0.x will increase coverage by 0.10%.
The diff coverage is 20.00%.

@@             Coverage Diff              @@
##              3.0.x    #4059      +/-   ##
============================================
+ Coverage     78.09%   78.19%   +0.10%     
+ Complexity     4603     4588      -15     
============================================
  Files           189      188       -1     
  Lines         11552    11527      -25     
============================================
- Hits           9021     9014       -7     
+ Misses         2531     2513      -18     

Impacted Files	Coverage Δ	Complexity Δ
src/Tools/Console/Command/ReservedWordsCommand.php	0.00% <0.00%> (ø)	12.00 <1.00> (-4.00)
src/Tools/Console/ConsoleRunner.php	0.00% <0.00%> (-11.12%)	3.00 <2.00> (-4.00)
src/Tools/Console/Command/RunSqlCommand.php	97.29% <100.00%> (+8.66%)	10.00 <1.00> (-4.00)	⬆️
...le/ConnectionProvider/SingleConnectionProvider.php	60.00% <0.00%> (+60.00%)	4.00% <0.00%> (ø%)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3710903...905f0a0. Read the comment docs.

[morozov]

Thanks, @dmaicher.