About dialog changes tooltip theme from Light to Dark

### Windows Terminal version

1.18.2822.0

### Windows build number

10.0.19045.0

### Other Software

_No response_

### Steps to reproduce

Use a Dark application theme. Open a new Terminal window and take note of the tooltip theming. Open the About dialog and close it and then recheck tooltip theming.

### Expected Behavior

_No response_

### Actual Behavior

I noticed this behaviour today, and I can consistently reproduce it. When I open a new Terminal window, the tooltips for that window are Light themed up until I open the About dialog, and then they become Dark themed (but only for that window). You can see what I mean in the following video:

https://github.com/microsoft/terminal/assets/11712728/cf716feb-d02a-4017-8e56-d35d7b51d2d8

In my `settings.json`, I'm using this custom Dark theme (the purpose is just to allow me to hide the close buttons on the tabs):

"theme": "dark_no-close-button",
"themes":
[
{
"name": "dark_no-close-button",
"tab":
{
"background": "terminalBackground",
"showCloseButton": "never",
"unfocusedBackground": "#00000000"
},
"tabRow":
{
"background": "#2E2E2EFF",
"unfocusedBackground": "#333333FF"
},
"window":
{
"applicationTheme": "dark",
"useMica": false
}
}
]

It happens when I just use `"theme": "dark"` or `"theme": "legacyDark"` as well though.

Here are my Windows colour settings:


Reproduce the issue using the reported Windows Terminal version, dark application themes, and the About dialog steps. Trace the About dialog and tooltip theme handling to find why the window changes from Light to Dark. Done means tooltip theming stays consistent before and after opening and closing About, with a regression test if the existing test structure supports it.

Written by the indexing model from the issue text.