TH09: Don't play the title screen BGM for a few milliseconds before switching to the conversation BGM

[nmlgc]

You don't hear this in the original game since the title screen BGM starts with ~1.9s of silence, but it will become a mild annoyance for BGM modders, who currently have to remember to also start their modded title screen BGM with some small (and probably undefined?) amount of silence to work around this issue.

[nmlgc]

A similar, even smaller and probably harder to fix issue happens in TH11 Stage 6, which immediately starts playing a few milliseconds of the Stage 6 BGM, then pauses playback, and only resumes it ~4.9 seconds later.