Camera: Disable result dump for cacheDump

cacheDump is called unconditionally during camera closing.
However, dump() is expensive especially when the metadata
is large.

Do not dump result metadata in this case.

Test: repeatedly close camera and observe cacheDump latency
Flag: EXEMPT bugfix
Bug: 439935681
Change-Id: I1941643ac57d54ef8b3a8b75524f88477f9da904