Ads Panel in 0.61x should have Ads Coming Soon

[mandar-brave]

Please see issue created by @LaurenWags for 0.60 for details below.
Status quo for 0.61 - #3421

Original plan is here: #3141

cc @jsecretan @bbondy @rebron

[jsecretan]

Ads will finally go to production on 0.63.

[ryanml]

This was done via: brave/brave-core#1793

[srirambv]

Verification passed on

Brave	0.61.46 Chromium: 73.0.3683.39 (Official Build) beta (64-bit)
Revision	cc53b0e12fcaf42e4bab8d6c23bd4fb7aae99f6c-refs/branch-heads/3683@{#413}
OS	Linux

• Can't test with old profile with ads enabled on Linux as its still not supported
  

Verification passed on

Brave	0.61.46 Chromium: 73.0.3683.39 (Official Build) beta (64-bit)
Revision	cc53b0e12fcaf42e4bab8d6c23bd4fb7aae99f6c-refs/branch-heads/3683@{#413}
OS	Windows 7 Service Pack 1 Build 7601.24312

Verification PASSED on macOS 10.14.3 x64 using the following build:

Brave	0.61.48 Chromium: 73.0.3683.56 (Official Build) beta(64-bit)
Revision	303af44e2f2948869279f120021c778855d76ead-refs/branch-heads/3683@{#653}
OS	Mac OS X

• Went through the test plan outlined under Disables Ads on 0.61 brave-core#1793
• Launched using --enable-logging=stderr --vmodule=brave_ads=3 --log-level=0 using a brand new profile and ensured there was no ads logging
• Launched using --enable-logging=stderr --vmodule=brave_ads=3 --log-level=0 using a profile that already had ads enabled and ensured that there wasn't any ad logs.