revert: try to coalesce screen updates

[KristofferC]

Effectively reverts #39538 since this code is now:

• dead by default (delay is 0.0 on all platforms)
• doesn't seem to improve anything, even when bracket paste is not supported
• bracket paste is now supported on Windows

Ref #59827 (comment)

[vtjnash]

IIUC, this is for post v1.13 branch merge (so the code is available in v1.13 in case someone is using a recent version that doesn't support bracketed paste and wants to re-enable it locally). I don't know what other bugs were introduced such that pressing each individual key now is very slow

[KristofferC]

I don't know what other bugs were introduced such that pressing each individual key now is very slow

Could you elaborate on this?

[vtjnash]

When originally merged, that PR could render the whole screen update for that amount of text in less than a second even on Windows, and now apparently it can't.