submodule: bump third_party/openthread/repo from `173cb61` to `347093… #5418

Job	Run time
Border Router (mDNSResponder)	29m 25s
Border Router (Avahi)	29m 33s
Border Router TREL (mDNSResponder)	29m 44s
Border Router TREL (Avahi)	28m 57s
Border Router MATN (mDNSResponder)	17m 57s
Border Router Internet Access Features (mDNSResponder)	26m 21s
Backbone Router	17m 21s
Border Router TREL with FEATURE_FLAG (avahi)	29m 5s
	3h 28m 23s

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