Fix creating ConnectivityUtil to work on any platform

After this CL, ConnectivityUtil for default subId is used again on pre
N because TelephonyManager has createForSubscriptionId() for a specific
subId from N.
Nevertheless, listen() uses the default subId on PhoneStateListener
instead of the subId on the manager still even N. On O and beyond,
ConnectivityUtil works correctly on multi-sim devices.

Revert "Fix missing computeIfAbsent() method in L_MR1 and M"

This reverts commit f0ccb76d8d9585846a7f5e7a83520ddcba057b26.

Reason for revert: Manage ConnectivityUtil instances for subIds at least
                   on N instead.

Test: Manual

Signed-off-by: Taesu Lee <taesu82.lee@samsung.com>
Change-Id: I2f08928a6798a2ce275c5c75569ad379999d274c
2 files changed