Fix remaining test cases

[yikjunxian]

Fixed test cases for RoleCommandTest, RoleTest and PhoneContainsKeywordsPredicateTest.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Files with missing lines	Coverage Δ	Complexity Δ
...java/seedu/address/logic/commands/RoleCommand.java	61.79% <100.00%> (ø)	9.00 <0.00> (?)
src/main/java/seedu/address/model/role/Role.java	71.42% <100.00%> (ø)	6.00 <0.00> (?)

... and 12 files with indirect coverage changes