Force p10k shell integration on when available to fix hanging problem for old versions

[Tyriar]

Repro:

1. Install powerlevel10k
2. cd powerlevel10k
3. git fetch --unshallow --all - should fetch all repo commits
4. git checkout 2b7da93 - should repro hanging
5. Open chat
6. Ask Run in terminal: ls, 🐛 this shouldn't hang

Context: #271897 (comment)

[meganrogge]

i've been using p10k in zsh and haven't seen this. Is it only for a specific version though? @Tyriar