Fix BLE advertising state machine (#2330)
Fix BLE advertising state machine (#2330)

Disabling advertising via SetAdvertisingEnabled(false) does not
currently work because kFlag_Advertising is not set, and the wrong flag
is checked in DriveBLEState, and HandleConnectionCloseEvent may throw a
wrench in things by messing directly with the advertising flag.
nestlabs/connectedhomeip,project-chip/connectedhomeip,project-chip/connectedhomeip,project-chip/connectedhomeip,nestlabs/connectedhomeip,nestlabs/connectedhomeip,project-chip/connectedhomeip,nestlabs/connectedhomeip,project-chip/connectedhomeip,nestlabs/connectedhomeip,project-chip/connectedhomeip,nestlabs/connectedhomeip,nestlabs/connectedhomeip