MONGOID-5839 Fix eager-loading from STI subclasses (backport to 9.0-stable) #3892

Job	Run time
ruby-3.3 drv:current db:7.0 rails: fle: replica_set	14m 24s
ruby-3.2 drv:current db:6.0 rails: fle: replica_set	13m 44s
ruby-3.1 drv:current db:6.0 rails: fle: replica_set	13m 38s
ruby-3.0 drv:stable db:6.0 rails: fle: replica_set	14m 4s
ruby-3.3 drv:current db:7.0 rails:8.0 fle:helper server	12m 46s
ruby-3.2 drv:current db:7.0 rails:7.2 fle:helper server	12m 31s
ruby-3.2 drv:current db:7.0 rails:7.1 fle:helper server	12m 22s
ruby-3.1 drv:current db:7.0 rails:7.0 fle:helper server	12m 41s
ruby-3.1 drv:current db:6.0 rails:6.1 fle:helper server	12m 33s
ruby-3.0 drv:current db:6.0 rails:6.1 fle:helper server	13m 8s
ruby-3.0 drv:current db:6.0 rails:6.0 fle:helper server	12m 51s
jruby-9.4 drv:current db:6.0 rails:6.0 fle:helper server	23m 9s
ruby-3.1 drv:current db:5.0 rails: fle: replica_set	13m 48s
ruby-2.7 drv:current db:4.4 rails: fle: replica_set	14m 1s
	3h 15m 40s

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