Fix: avoid ignore plain text in input-group-$size

[mendozagioo]

Fixes #29605

[MartijnCuppens]

Issue: https://codepen.io/MartijnCuppens/pen/dyPoOKM
Fix: https://codepen.io/MartijnCuppens/pen/KKwpNBx

It seems the inputs aren't aligned due to the border. Is this issue also present in master?

[ysds]

@MartijnCuppens Dropped in #28972

[mendozagioo]

Hey @MartijnCuppens, in master branch is worst, the input is out of line. The problem here is that form-control-plaintext class is considered just for remove border and color but not is considered to use like child of input-group class. The fix, just it add form-control-plaintext class to be used inside of input-group class

[MartijnCuppens]

This PR need some additional tweaks to fix the issues with the border. Not sure if it's worth fixing this if we drop this if we drop this in master anyway.

\CC @twbs/css-review

[mdo]

This PR need some additional tweaks to fix the issues with the border. Not sure if it's worth fixing this if we drop this if we drop this in master anyway.

It is indeed not worth it :).