UI: Fix low value of std::clamp gets greater than high value

[norihiro]

Description

This commit partially reverts 60a45d3aa3 to avoid a runtime assertion failure on Windows that checks the low value of std::clamp is not greater than the high value.

To clarify the necessity to consider the priority, I didn't revert to use the CLAMP macro but use an if-else-if statement.

Motivation and Context

I modified to use std::clamp in the PR #11167. However, @exeldro reported it caused a runtime error on Windows.

I confirmed the low value (currentPeak[channelNr]) gets greater than the high value (0.f) by applying a gain filter with a large gain.

How Has This Been Tested?

OS Fedora 39

Applied a gain filter with a large gain.

Checked the other std::clamp usage, I checked minimumLevel never gets larger than 0 by eyeball. https://github.com/obsproject/obs-studio/blob/8251005ad3acb54a67b68e2cb0846a783f0aeed7/UI/volume-control.cpp#L1062-L1064

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• [x] My code has been run through clang-format.
• [x] I have read the contributing document.
• [ ] My code is not on the master branch.
• [x] The code has been tested.
• [x] All commit messages are properly formatted and commits squashed where appropriate.
• [x] I have included updates to all appropriate documentation.