Member completion uses wrong qualifier

[auduchinok]

Consider the following example:

let f (s: string) =
    s.Trim()
    s.Trim()
    s.Trim()
    ()

It's expected that the member code completion is the same after each s.Trim() invocation, however, members are suggested in the first case only, and the next two cases suggest unqualified items:

Initially reported in RIDER-120178.

[auduchinok]

The issue has been introduced in #16882. cc @brianrourkeboll

Commenting out the following fixes a test case I've added:

fsharp/src/Compiler/Service/ServiceParseTreeWalk.fs

Lines 715 to 721 in 3940e0d

	// Nested sequentials.
	| SynExpr.Sequential(expr1 = synExpr1; expr2 = synExpr2 & SynExpr.Sequential _) ->
	[
	dive synExpr1 synExpr1.Range traverseSynExpr
	yield! traverseSequentials path synExpr2
	]
	|> pick expr

See the test in this branch:
https://github.com/auduchinok/fsharp/blob/3904ceda0089f3799eff70eabf2963af8c7e5f3d/tests/FSharp.Compiler.Service.Tests/CompletionTests.fs#L124