Revert "feat(streaming): memory-size-based back-pressure in exchange"

[wangrunji0408]

Reverts #13775 due to performance degradation.

[MrCroxx]

Some contexts: #13775 may cause the actor throughputs of the same fragment are not balanced.

wo/w #13375:

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (1d99124) 68.23% compared to head (6efe5ce) 68.29%.
Report is 2 commits behind head on main.

Files	Patch %	Lines
src/stream/src/executor/exchange/input.rs	0.00%	1 Missing ⚠️
src/stream/src/executor/exchange/permit.rs	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13822      +/-   ##
==========================================
+ Coverage   68.23%   68.29%   +0.06%     
==========================================
  Files        1525     1525              
  Lines      262308   262307       -1     
==========================================
+ Hits       178975   179139     +164     
+ Misses      83333    83168     -165     

Flag	Coverage Δ
rust	68.29% <88.88%> (+0.06%)	⬆️

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