Fix dotted border on disabled TextField global style

[pawelgrimm]

Issue:

Acceptance criteria:

• when timer is running, field no longer displays underline
  

MuiFilledInput-underline.Mui-disabled::before {
    border-bottom-style: dotted; // Change to hidden
}

[pawelgrimm]

Could also add bottom radius when disabled:

.MuiInputBase-root.Mui-disabled {
    color: rgba(255, 255, 255, 0.5);
    cursor: default;
    // border-radius: 4px;
}