pex: switch to SCIE binary instead of PEX #25011

Job	Run time
Classify changes	4s
Bootstrap Pants, test Rust (Linux-ARM64)	1m 15s
Bootstrap Pants, test and lint Rust (Linux-x86_64)	2m 14s
Build wheels (Linux-ARM64)	0s
Bootstrap Pants, test Rust (macOS13-x86_64)	5m 18s
Build wheels (Linux-x86_64)	0s
Build wheels (macOS13-x86_64)	0s
Build wheels (macOS14-ARM64)	0s
Ensure PR has release notes	3s
Test Python (Linux-ARM64)	0s
Test Python (Linux-x86_64) Shard 1/10	5m 37s
Test Python (Linux-x86_64) Shard 0/10	5m 36s
Test Python (Linux-x86_64) Shard 2/10	5m 35s
Lint Python and Shell	2m 56s
Test Python (Linux-x86_64) Shard 3/10	5m 36s
Test Python (Linux-x86_64) Shard 4/10	5m 37s
Test Python (Linux-x86_64) Shard 5/10	5m 36s
Test Python (Linux-x86_64) Shard 6/10	5m 35s
Test Python (Linux-x86_64) Shard 7/10	5m 35s
Test Python (Linux-x86_64) Shard 8/10	5m 35s
Test Python (Linux-x86_64) Shard 9/10	5m 36s
Test Python (macOS13-x86_64)	2m 58s
Set Merge OK	1s
Merge OK	1s
	1h 10m 48s

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