Brave Wallet shouldn't write properties from ethereum provider object

[darkdh]

Currently Brave would write ALL properties of window.ethereum multiple times even default wallet setting is "Prefer Extensions"

1. when page loaded
2. when users change network on Brave wallet or account changed.
3. when uses triggered accountsChanged

Note that 1st scenario doesn't require users action, here is an example that it interferes with extensions like MetaMask

1. Set default wallet setting to "Prefer Extensions"
2. Set network on Brave Wallet to Polygon(0x89) and set network on MetaMask to Mainnet(0x1)
3. Load simple page like https://example.com/
4. Open console and type ethereum.chainId
5. We would see 0x89 instead of 0x1

[srirambv]

Verification passed on

Brave	1.43.81 Chromium: 104.0.5112.102 (Official Build) (64-bit)
Revision	8e5396254975ef939f2ef7d0bd334e48a052b536-refs/branch-heads/5112@{#1478}
OS	Linux

• Verified steps from brave/brave-core#14539 & regression test
• Verified chainid is 0x1 instead of 0x89

24531-Linux.mp4

---

Verification passed on

Brave	1.43.81 Chromium: 104.0.5112.102 (Official Build) (64-bit)
Revision	8e5396254975ef939f2ef7d0bd334e48a052b536-refs/branch-heads/5112@{#1478}
OS	Windows 11 Version 21H2 (Build 22000.795)

• Verified steps from brave/brave-core#14539 & regression test
• Verified chainid is 0x1 instead of 0x89

24531.-.Windows.mp4

---

Verification passed on

Brave	1.43.81 Chromium: 104.0.5112.102 (Official Build) (arm64)
Revision	8e5396254975ef939f2ef7d0bd334e48a052b536-refs/branch-heads/5112@{#1478}
OS	macOS Version 12.4 (Build 21F79)

• Verified steps from brave/brave-core#14539 & regression test
• Verified chainid is 0x1 instead of 0x89

24531-macOS.mov