Add missing close in sending uidMap

Add missing close call to write side of the uid map pipe. More context
in b/286471361.

Test: verified with traces that informAllUidData no longer blocks
Test: builds, boots
Bug: 286471361
Ignore-AOSP-First: needed in UDC
Change-Id: I875027722aba1d681b0b0cd5c210761e81da6e4c
1 file changed