Autoplay will have ask prompt if global content setting is toggled

[darkdh]

Description

Steps to Reproduce

1. Visit brave://settings/content/autoplay
2. Toggle the label from "Allowed"=>"Blocked" and then "Blocked"=>"Allowed
3. Visit https://www.youtube.com/
4. The prompt shows up

Actual result:

Expected result:

There shouldn't be any prompt when content setting can only be set to block or allow

Reproduces how often:

Brave version (brave://version info)

Version/Channel Information:

• Can you reproduce this issue with the current release?
• Can you reproduce this issue with the beta channel?
• Can you reproduce this issue with the nightly channel?

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
• Does the issue resolve itself when disabling Brave Rewards?
• Is the issue reproducible on the latest version of Chrome?

Miscellaneous Information:

[GeetaSarvadnya]

Verification passed on

Brave | 1.19.61 Chromium: 87.0.4280.101 (Official Build) dev (64-bit)
-- | --
Revision | 9407c80213cda69c2b7abcb4fa8e3f74488f4956-refs/branch-heads/4280@{#1807}
OS | Windows 10 OS Version 2004 (Build 19041.685)

• Verified the STR from the description
• Verified that there is no prompt when content setting is set to block or allow

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Verification passed on

Brave	1.19.66 Chromium: 87.0.4280.101 (Official Build) dev (64-bit)
Revision	9407c80213cda69c2b7abcb4fa8e3f74488f4956-refs/branch-heads/4280@{#1807}
OS	Ubuntu 18.04 LTS

Reproduced the issue on 1.18.x

• Verified the STR from the description
• Prompt was not shown
  

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Verification PASSED on macOS 11.1 x64 using the following build:

Brave | 1.19.81 Chromium: 87.0.4280.141 (Official Build) dev (x86_64)
--- | ---
Revision | 9f05d1d9ee7483a73e9fe91ddcb8274ebcec9d7f-refs/branch-heads/4280@{#2007}
OS  | macOS Version 11.1 (Build 20C69)

Reproduced the original issue with 1.18.78 CR: 87.0.4280.141 using the STR/Cases outlined via #12795 (comment) as per the following:

Verified that the issue isn't occurring with 1.19.81 CR: 87.0.4280.141