[Clean/iniTest] add logic to erase ini after test

[Clean/iniTest] add logic to erase ini after test

This patch add logic to erase ini after test for better determinancy
and cleaner build directory.

v2: also deprecating config_str in favor of
`ScopedIni`

**Self evaluation:**
1. Build test: [X]Passed [ ]Failed [ ]Skipped
2. Run test: [X]Passed [ ]Failed [ ]Skipped

Signed-off-by: Jihoon Lee <jhoon.it.lee@samsung.com>