Emit connect-related metrics for dcQUIC streams

[Mark-Simulacrum]

Problem:

See TODO added here - https://github.com/aws/s2n-quic/pull/2675#discussion_r2155152975

We need metrics on stream connection success - even if we weren't responsible for the TCP connect (what was added in the PR above).

Need By Date:

None currently.

Solution:

• Does this change what s2n-quic sends over the wire? no
• Does this change any public APIs? yes (new metrics/events)

Requirements / Acceptance Criteria:

n/a

Out of scope:

n/a