DTPORTAL-16979 Prevent inappropriate transcoding

[sfgeorge]

Fix corrupted audio on outbound calls by assuring that we set packetization time. Addresses unispeech/asterisk-unimrcp#37

This fix follows 869ef2a's partial fix to add_sdp(). In that previous fix, only inbound legs were fixed. This PR ensure that that fix applies to outbound legs as well.

Context:

• UniMRCP has always written packets of size 10ms.
• Previously, Asterisk would correct this behavior with its RTP "Smoother", regulating outgoing packets to be of the size that has been negotiated - in our case 20ms.
• The RTP "Smoother" is not initialized if the RTP Instance lacks a packetization time, or framing_ms. (This shouldn't ever occur... but it does under Asterisk 13 for some still unknown reason).
• A quick-fix was added in 869ef2a, but was only ever applied to heal inbound calls and not outbound ones.
• This PR broadens that quick-fix to heal outbound calls as well.

[sfgeorge]

Sadness. This didn't work. Going to go with an alternate approach.