cmd/go/internal/modload: rename constants to reflect that lazy loading is not yet implemented
cmd/go/internal/modload: rename constants to reflect that lazy loading is not yet implemented

Updates #36460
Updates #42288

Change-Id: I82a3b7e97a8e2f83bae2318ca9fb5c38c0c811cd
Reviewed-on: https://go-review.googlesource.com/c/go/+/275172
Trust: Bryan C. Mills <1c8aad60184261ccede67f5c63a0d2a3bf3c9ff4@google.com>
Run-TryBot: Bryan C. Mills <1c8aad60184261ccede67f5c63a0d2a3bf3c9ff4@google.com>
Reviewed-by: Jay Conrod <f3fadaedc813344da5ec13b41e26596889cc5baa@google.com>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

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