Fix default slab_alloc_factor value (#3358)

Resolves #3357

Author: p7nov

doc/reference/configuration/cfg_storage.rst

@@ -95,7 +95,7 @@
     See also: :ref:`slab_alloc_granularity <cfg_storage-slab_alloc_granularity>`
 
     | Type: float
-    | Default: 1.1
+    | Default: 1.05
     | Environment variable: TT_SLAB_ALLOC_FACTOR
     | Dynamic: no
 

doc/reference/reference_lua/box_cfg.rst

@@ -17,7 +17,7 @@ To view the current configuration, say ``box.cfg`` without braces:
     ---
     - checkpoint_count: 2
       too_long_threshold: 0.5
-      slab_alloc_factor: 1.1
+      slab_alloc_factor: 1.05
       memtx_max_tuple_size: 1048576
       background: false
       <...>