Improve text on aggressive mode interstitial to explain link to aggressive mode

[pes10k]

Some users are surprised when they see the interstitial appear in aggressive mode.

https://bravesoftware.slack.com/archives/C6YNM6Y5S/p1683211033792949

It would be good to add additional text stating (straw text)

• this is because of aggressive mode
• brave by default protects your privacy on every site you visit
• this dialog is an extra aggressive warning that you're visiting a site that may be privacy-hostile

[pilgrim-brave]

Proposed text: "Because you requested to aggressively block trackers and ads, Brave is blocking this site before the first network connection."

[LaurenWags]

@pilgrim-brave @pes10k could one of you please provide a test plan for this one as it's labeled QA/Yes. Thanks!

[pes10k]

@LaurenWags this should work:

1. visit https://antitracking.owncast.online/ with aggressive blocking
2. verify that the text has been changed and matches @pilgrim-brave 's screenshot above

[LaurenWags]

Thanks @pes10k!

[stephendonner]

Verified PASSED using

Brave	1.57.2 Chromium: 115.0.5790.56 (Official Build) beta (x86_64)
Revision	ebcfb87c1393f36955cfa2f6451a1767e3dc3ee5-refs/branch-heads/5790@{#1193}
OS	macOS Version 11.7.8 (Build 20G1351)

Steps:

1. installed 1.57.2
2. launched Brave
3. loaded https://antitracking.owncast.online/
4. confirmed no interstitial-blocking message
5. switched to Aggressively block trackers & ads in the Shields dropdown
6. confirmed page reloaded, now with intersitial-blocking message
7. clicked on Proceed
8. confirmed I was shown https://antitracking.owncast.online/ without the interstitial

example	example	example	example	example

[hffvld]

Verified on Pixel 7 using version(s):

Device/OS: Pixel 7 [panther_beta-user 14 UPB4.230623.007 release-keys]
Brave build: 1.57.33
Chromium: 115.0.5790.114 (Official Build) beta (64-bit) 
Revision: 86b4ea1d70ce73c4468d84cc8277f1f9de14b8bc

---

STEPS:

1. Launch Brave
2. Three-dot menu > Settings > Brave Shields & privacy
3. Block trackers & ads > Allow all trackers & ads > Done
4. Close settings and open https://antitracking.owncast.online/ > Verify
5. Now change Block trackers & ads to Block trackers & ads (Standard) > Done
6. Close settings and open https://antitracking.owncast.online/ > Verify
7. Now change Block trackers & ads to Block trackers & ads (Aggressive) > Done
8. Close settings and open https://antitracking.owncast.online/ > Verify

ACTUAL RESULTS:

• Verified that no interstitial-blocking message is shown when Block trackers & ads is set to Allow all trackers & ads or Block trackers & ads (Standard)
• Verified that page reloaded when Block trackers & ads updated to Block trackers & ads (Aggressive) and now shows intersitial-blocking message
• Verified when Block trackers & ads is set to Block trackers & ads (Aggressive) and intersitial-blocking message is shown, tapping Proceed is loading proper page

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Allow all trackers & ads	Block trackers & ads (Standard)	Block trackers & ads (Aggressive)
1	2	3
1	2	3
1	2	3