Whitelist XCM Storage Read Each block from Benchmarking

[shawntabrizi]

For example:

// Storage: XcmPallet SupportedVersion (r:1 w:0)
// Storage: XcmPallet VersionDiscoveryQueue (r:1 w:1)
// Storage: XcmPallet SafeXcmVersion (r:1 w:0)
// Storage: Configuration ActiveConfig (r:1 w:0)

All of these storage items are read each block, and thus do not also need to be included into the main benchmark weights.

See: #4442

[KiChjang]

I think a7a5387 addresses this.

[KiChjang]

Actually, I didn't add the XCM pallet's storage items, as I wasn't sure if they're really read each block.

[shawntabrizi]

I think the assumption is that you should expect at least one XCM message present each Polkadot block, so yeah, all of them would be whitelisted.

But would be best we actually design this whitelisting in the FRAME macros.

[franciscoaguirre]

This was fixed in #6871