fix: recorder memory usage when a user rejoins

[TyrantKingBen]

Pull Request Type

• Feature addition
• Bugfix
• Documentation update
• Code refactor
• Tests improvement
• CI/CD pipeline enhancement
• Other: [Replace with a description]

Description

This fixes some erroneous code that cause enormous memory usage when rejoining a voice channel with a bot recording.

Changes

• Fix calculation of how long of silence to add when a user rejoins a recorded voice channel.

Related Issues

Fixes #1642.

Test Scenarios

Use whatever you prefer and start monitoring your system memory usage. Join a voice channel and have a bot join it to record. Talk and then disconnect from the voice channel. Wait 3-5 seconds and rejoin the voice channel. Memory usage should stay relatively the same. Stop the recording and confirm the recorded audio is correct.

Python Compatibility

• I've ensured my code works on Python 3.10.x
• I've ensured my code works on Python 3.11.x

Checklist

• I've run the pre-commit code linter over all edited files
• I've tested my changes on supported Python versions
• I've added tests for my code, if applicable
• I've updated / added documentation, where applicable