Prevent Intent from initiating special-char handling

TESTED:
- Manually type "123#"
-> Should cause special-char-sequence handling

- Have Intent with "tel:123%23"
-> Should *not* cause the handling

- Try other USSD sequences
-> Should behave similarly as shown above

Bug: 6726923
Change-Id: Ic5b042f620b10931fedcaf12bb58be2405bf7390