Merge branch '3659-Q-reject_button_color_issue' into 'v1-q'

3659-Q-reject_button_color_issue

## Description
- reject button looks not good with accent color. reverse back to white color


## Issue(s)
- e/backlog#3659

## Test environment

<How to prepare the test environment>
- build apk against `3659-Q-reject_button_color_issue` feature branch & install in the device

## Test procedures

<What should be performed with this MR>
- go to dialer app, make any call check the reject button.
- or, receive any phone call, check the reject button.

In both cases, button should be white in red color.

## Technical details

<Any relevant detail regarding choicies for the implementation>
- use hard-coded white color instead of sdk color.

## Screenshots

<Screenshots of the MR results>
![Screenshot_20210826-213714_Phone](/uploads/52a8ba18df77e5f581ba4605361e96ee/Screenshot_20210826-213714_Phone.png)

## Check list

- [X] Self review
- [X] Test procedure explained
- [X] Tested on fresh install
- [X] Tested applied as an update
- [ ] License
- [ ] Internal documentation
- [ ] User documentation

See merge request e/os/android_packages_apps_Dialer!42