Use Length property instead of GetFileInformationByHandleEx for Seek(…

[jozkee]

…SeekOrigin.End)

Continuation of #49975.

Instead of always perform an expensive native call, we can take advantage of the caching logic in WindowsFileStream.Length which caches the result of GetFileInformationByHandleEx in memory when the file is locked.

Benchmark Results:

Method	Toolchain	fileSize	options	Mean	Error	StdDev	Median	Min	Max	Ratio	Allocated
SeekForward	\base\CoreRun.exe	1024	None	44.25 us	0.727 us	0.680 us	44.32 us	42.80 us	45.43 us	1.00	224 B
SeekForward	\feature\CoreRun.exe	1024	None	43.97 us	0.468 us	0.438 us	43.97 us	43.35 us	44.59 us	0.99	224 B
SeekBackward	\base\CoreRun.exe	1024	None	1,836.67 us	34.760 us	27.138 us	1,830.33 us	1,803.24 us	1,909.43 us	1.00	224 B
SeekBackward	\feature\CoreRun.exe	1024	None	46.98 us	0.622 us	0.551 us	47.03 us	45.66 us	47.69 us	0.03	224 B
SeekForward	\base\CoreRun.exe	1024	Asynchronous	44.77 us	0.646 us	0.605 us	44.92 us	43.81 us	45.99 us	1.00	272 B
SeekForward	\feature\CoreRun.exe	1024	Asynchronous	47.20 us	0.874 us	0.817 us	47.01 us	45.72 us	48.95 us	1.05	272 B
SeekBackward	\base\CoreRun.exe	1024	Asynchronous	2,697.63 us	31.490 us	29.456 us	2,697.93 us	2,642.54 us	2,760.08 us	1.00	272 B
SeekBackward	\feature\CoreRun.exe	1024	Asynchronous	50.21 us	0.508 us	0.475 us	50.05 us	49.59 us	51.08 us	0.02	272 B

[adamsitnik]

LGTM, thank you @jozkee !