Replace max_value_length on env with new engine options for max field and result chars

[rowanseymour]

Should never have been an env setting because it's engine level

[codecov]

Codecov Report

Merging #1175 (44e3bed) into main (66d4bb2) will increase coverage by 0.01%.
The diff coverage is 93.10%.

@@            Coverage Diff             @@
##             main    #1175      +/-   ##
==========================================
+ Coverage   87.80%   87.81%   +0.01%     
==========================================
  Files         258      258              
  Lines       10943    10944       +1     
==========================================
+ Hits         9608     9611       +3     
+ Misses        917      915       -2     
  Partials      418      418              

Files Changed	Coverage Δ
envs/environment.go	96.92% <ø> (-0.27%)	⬇️
flows/modifiers/channel.go	91.66% <ø> (ø)
flows/modifiers/groups.go	96.07% <ø> (ø)
flows/modifiers/language.go	100.00% <ø> (ø)
flows/modifiers/status.go	100.00% <ø> (ø)
flows/modifiers/timezone.go	83.33% <ø> (ø)
flows/modifiers/urn.go	100.00% <ø> (ø)
flows/modifiers/urns.go	100.00% <ø> (ø)
flows/engine/session.go	74.29% <50.00%> (ø)
flows/actions/base.go	91.13% <100.00%> (+0.05%)	⬆️
... and 6 more

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