Remove obsolete CFEI/CFSI optimization from ASM generation

[ironcev]

Description

This PR:

• removes the special handling of CFEI/CFSI instructions from the asm_lang and asm_generation. That special handling was introduced in cfei: don't generate if frame size is zero #5588 as an implementation of removal of CFEI/CFSI pairs if the allocated size was zero. Later on, Remove redundant cfe(i)/cfs(i) instructions from the allocated ASM #6627 implemented a general CFE(I)/CFS(I) removal as a localized optimization of the allocated abstract instruction set, but it did not removed the special handling introduced by cfei: don't generate if frame size is zero #5588.
• removes emitting of a CFEI for allocating globals, if the ASM does not have any globals.

Checklist

• I have linked to any relevant issues.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation where relevant (API docs, the reference, and the Sway book).
  • If my change requires substantial documentation changes, I have requested support from the DevRel team
• I have added tests that prove my fix is effective or that my feature works.
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
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[cursor]

PR Summary

Medium Risk
Changes compiler bytecode layout and jump-offset accounting, but behavior should stay equivalent because zero stack ops are still removed earlier in the allocated-abstract pipeline; regressions would show up as wrong jumps or VM failures.

Overview
Removes redundant zero-size CFEI/CFSI handling from bytecode emission and instruction-size math, so stripping those ops happens only in AllocatedAbstractInstructionSet::remove_redundant_ops (and related stack optimizations) instead of also in to_fuel_asm and jump/offset sizing.

Globals prologue: append_globals_allocation no longer inserts CFEI when the globals section is empty, which drops the former cfei i0 ; allocate stack space for globals from script entry prologues.

Offset helpers (op_size_in_bytes, worst_case_instruction_size, instruction_size_not_far_jump) now treat CFEI/CFSI like normal 4-byte ops because zero-immediate forms should not reach those paths. E2E ASM snapshots are updated accordingly.

^{Reviewed by Cursor Bugbot for commit 90e73d0. Bugbot is set up for automated code reviews on this repo. Configure here.}

[ironcev]

👍

[codspeed-hq]

Merging this PR will not alter performance

✅ 25 untouched benchmarks

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_{Comparing ironcev/remove-misplaced-cfei-cfsi-optimization (90e73d0) with master (08dad8c)}