Remove the OnSessionReleased callback from OperationalSessionSetup.

[bzbarsky-apple]

Since OperationalSessionSetup is ephemeral, it only holds on to a session while it's notifying its listeners, after which it will delete itself.

Right now it was deleting itself from OnSessionReleased, but that means it could end up with a double-delete... and also, it's already notifying listeners if it has a session, so there is no point, or ability, to notify them again on session release.

The changes here:

1. Take out the OnSessionReleased that couldn't do anything except lead to use-after-free.
2. Fix a bug on OnSessionEstablished where if we got a session that's not usable we leaked and left our listeners hanging instead of just notifying our listeners with error.

[github-actions]

PR #26395: Size comparison from ed8d546 to e3fe5c7

Increases (1 build for cc32xx)

platform	target	config	section	ed8d546	e3fe5c7a	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL	.debug_abbrev	957621	957646	25	0.0

Decreases (1 build for cc32xx)

platform	target	config	section	ed8d546	e3fe5c7a	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL	(read only)	605066	604946	-120	-0.0
			.debug_aranges	101136	101040	-96	-0.1
			.debug_frame	341512	341260	-252	-0.1
			.debug_info	19609713	19608209	-1504	-0.0
			.debug_line	2666606	2666198	-408	-0.0
			.debug_loclists	1489165	1488858	-307	-0.0
			.debug_rnglists	94315	94243	-72	-0.1
			.debug_str	3108961	3108654	-307	-0.0
			.rodata	104362	104330	-32	-0.0
			.strtab	483384	483077	-307	-0.1
			.symtab	287328	287168	-160	-0.1
			.text	498580	498492	-88	-0.0

Full report (1 build for cc32xx)

platform	target	config	section	ed8d546	e3fe5c7a	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL		0	0	0	0.0
			(read only)	605066	604946	-120	-0.0
			(read/write)	204164	204164	0	0.0
			.ARM.attributes	44	44	0	0.0
			.ARM.exidx	8	8	0	0.0
			.bss	197576	197576	0	0.0
			.comment	206	206	0	0.0
			.data	1468	1468	0	0.0
			.debug_abbrev	957621	957646	25	0.0
			.debug_aranges	101136	101040	-96	-0.1
			.debug_frame	341512	341260	-252	-0.1
			.debug_info	19609713	19608209	-1504	-0.0
			.debug_line	2666606	2666198	-408	-0.0
			.debug_line_str	513	513	0	0.0
			.debug_loc	33340	33340	0	0.0
			.debug_loclists	1489165	1488858	-307	-0.0
			.debug_ranges	4984	4984	0	0.0
			.debug_rnglists	94315	94243	-72	-0.1
			.debug_str	3108961	3108654	-307	-0.0
			.ramVecs	780	780	0	0.0
			.resetVecs	64	64	0	0.0
			.rodata	104362	104330	-32	-0.0
			.shstrtab	265	265	0	0.0
			.stack	2048	2048	0	0.0
			.strtab	483384	483077	-307	-0.1
			.symtab	287328	287168	-160	-0.1
			.text	498580	498492	-88	-0.0