Add netblock anonymization verification test

[stephen-soltesz]

This change adds a new test for the triggertrace handler to verify that the output truly has netblock anonymization applied for v4 and v6 addresses.

This change adds a static definition of traces that include intermediate hops that should be anonymized in addition to the destination address.

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This change is 

[coveralls]

Pull Request Test Coverage Report for Build 546

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 95.983%

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Totals
Change from base Build 532:	0.0%
Covered Lines:	669
Relevant Lines:	697

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💛 - Coveralls

[SaiedKazemi]

internal/triggertrace/triggertrace_test.go line 291 at r2 (raw file):

  }

  staticIPv4Netblock = &parser.Scamper1{

Since it's very difficult to know what's different among these four initializations, does it make sense to do something like the following?

    staticIPv4Netblock = staticIPv4None
    staticIPv4None.Tracelb.Dst = "4.4.4.0" // NETBLOCK
    staticIPv4None.Tracelb.Nodes[0].Links = : [][]parser.ScamperLink{{{Addr: "4.4.4.0"}}} // NETBLOCK
    staticIPv4None.Tracelb.Nodes[1].Addr = "4.4.4.0" // NETBLOCK
    staticIPv4None.Tracelb.Nodes[1].Links = [][]parser.ScamperLink{{{Addr: "4.4.4.0"}}}, // NETBLOCK

So it's immediately clear what has changed?