It appears that template out-from-box targets only /usr mount, which does not report valuable triggers. The proposal is to replace:

{$BIGIP.LLD.OVERRIDE.PART.FILTER_LOW_SPACE_TRIGGER} = ^/usr$

with:

{$BIGIP.LLD.OVERRIDE.PART.FILTER_LOW_SPACE_TRIGGER} = ^/opt/\.sdm/(usr|lib|lib64)$|^/usr$

P.S. Vendor F5 says that everything under /usr partition is ReadOnly and does not need to be monitored also in the future on BIGIP v17.5.