hard refresh of Tor tab usually does not get new IP

[LaurenWags]

Description

Found while testing 'New circuit' from #1270 (comment) Most of the time when doing a hard refresh of Tor tab a new IP is not fetched. However, 'New Tor Identity' works each time.

Steps to Reproduce

1. Open Tor window.
2. Navigate to check.torproject.org or whatsmyip.org
3. Do hard refresh of the page --> IP may or may not change
4. Repeat step 3 a few times. --> IP does not change
5. Open a new tab in Tor window. Navigate to same site. --> same IP is displayed.

Actual result:

IP generally does not change. If you use 'New Tor Identity' you will get a new IP each time.

Expected result:

New IP without having to use 'New Tor Identity'.

Reproduces how often:

fairly easily, but sometimes IP does change.

Brave version (chrome://version info)

Brave	0.55.12 Chromium: 70.0.3538.45 (Official Build) beta(64-bit)
Revision	cbdc32e4334458954e9def214d7e5fa1ca1960eb-refs/branch-heads/3538@{#830}
OS	Mac OS X

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds? yes
• Does it reproduce on browser-laptop? no, hard refresh on 0.25.0 generates new IP

Website problems only:

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

Additional Information

Reproduced by @srirambv

[tildelowengrimm]

This functionality hasn't been implemented yet: #1137 is the open issue for this work.