Cherry pick tracer fix, release v1.6.1

[piersy]

Description

This PR cherry picks the tracer fix from #1968 and updates the version to v1.6.1 to be ready for release.

[piersy]

Coverage from tests in ./e2e_test/... for ./consensus/istanbul/... at commit 742551c895081dc270a690eb2dcbf2d4b2d592ce

coverage: 51.0% of statements across all listed packages

coverage:  64.0% of statements in consensus/istanbul
coverage:  42.7% of statements in consensus/istanbul/announce
coverage:  55.8% of statements in consensus/istanbul/backend
coverage:   0.0% of statements in consensus/istanbul/backend/backendtest
coverage:  24.3% of statements in consensus/istanbul/backend/internal/replica
coverage:  67.0% of statements in consensus/istanbul/core
coverage:  50.0% of statements in consensus/istanbul/db
coverage:   0.0% of statements in consensus/istanbul/proxy
coverage:  64.4% of statements in consensus/istanbul/uptime
coverage:  51.8% of statements in consensus/istanbul/validator
coverage:  79.2% of statements in consensus/istanbul/validator/random

CommentID: e9c7a12b29

[piersy]

We ended up cherry picking a bunch more stuff for v1.6.1 see #1977