pg_upgrade v15 not generating analyze_new_cluster.sh

[rihad]

Hi, all. When pg_upgrading from PG 11 to 13, a file 
analyze_new_cluster.sh was generated in the current directory which ran 
vacuumdb --all --analyze-in-stages

When upgrading from 13 to 15.3 no such file was generated, which made me 
believe it was no longer necessary. Alas, it wasn't the case. The 
database was extremely slow after the upgrade chewing up 100% cpu time, 
and it wasn't until I manually ran vacuumdb" --all --analyze-in-stages 
that cpu usage dropped. Was there a knob that I missed, or is this just 
a bug in pg_upgrade 15? Thanks.