fix broken insecureskipverify handling in rediss connection uris (#20967) (#21053)

fix broken insecureskipverify handling in rediss connection uris (#20967) (#21053)

Backport #20967

Currently, it's impossible to connect to self-signed TLS encrypted redis instances. The problem lies in inproper error handling, when building redis tls options - only invalid booleans are allowed to be used in `tlsConfig` builder. The problem is, when `strconv.ParseBool(...)` returns error, it always defaults to false - meaning it's impossible to set `tlsOptions.InsecureSkipVerify` to true.

Fixes #19213

Co-authored-by: Igor Rzegocki <ajgon@users.noreply.github.com>