objectcache: Actually unserialize integers as integers in RedisBagOStuff

Before:
> SET   (stored)    GET
>  5     5          (string) "5"
>  '5'   5          (string) "5"
>  'x'   s:1:"x";   (string) "x"

After:
> SET   (stored)    GET
>  5     5          (int) 5
>  '5'   s:1:"5";   (string) "5"
>  'x'   s:1:"x";   (string) "x"

Follows-up 2ceda41c5783ddc3cfb.

Bug: 60563
Change-Id: I2bb09381b2bb733ac5a89175e053cb10eca68b08
Merge "objectcache: Actually unserialize integers as integers in RedisBagOStuff"