Fix oversight in data-type change for autovacuum_vacuum_cost_delay.

Fix oversight in data-type change for autovacuum_vacuum_cost_delay.

Commit caf626b2c missed that the relevant reloptions entry needs
to be moved from the intRelOpts[] array to realRelOpts[].
Somewhat surprisingly, it seems to work anyway, perhaps because
the desired default and limit values are all integers.  We ought
to have either a simpler data structure or better cross-checking
here, but that's for another patch.

Nikolay Shaplov

Discussion: https://postgr.es/m/4861742.12LTaSB3sv@x200m