remove creating IPinIP tunnel for srv6 uN

[baorliu]

What I did
Remove the SAI_MY_SID_ENTRY_ENDPOINT_BEHAVIOR_UN condition in mySidTunnelRequired condition checking, do not create IPinIP tunnel for srv6 uN

Why I did it
For the node support srv6 uN only (not support uDT46), it might not implement SAI_TUNNEL_TYPE_IPINIP. creating IPinIP tunnel cause SAI API failed and failed to create SAI_OBJECT_TYPE_MY_SID_ENTRY.

Here is how the function fails in a uN only node:

2025 Jul 30 22:58:42.290917 sonic NOTICE swss#orchagent: :- doTask: table name : SRV6_MY_SID_TABLE
2025 Jul 30 22:58:42.291081 sonic NOTICE swss#orchagent: :- createUpdateMysidEntry: MySid: sid fcbb:bbbb:1::, action un, vrf , block 32, node 16, func 0, arg 0 dt_vrf , adj 
2025 Jul 30 22:58:42.291186 sonic NOTICE swss#orchagent: :- getMySidEntryDscpMode: Found decap DSCP mode for MySID addr fcbb:bbbb:1::/48 locator loc1 in the cache
2025 Jul 30 22:58:42.328456 sonic NOTICE swss#orchagent: :- initIpInIpTunnel: Created MySID IPinIP tunnel
2025 Jul 30 22:58:42.328510 sonic NOTICE swss#orchagent: :- createMySidIpInIpTunnel: Increased refcount for MySID IPinIP tunnel to 1
2025 Jul 30 22:58:42.387983 sonic ERR syncd#syncd: 30-07-2025 22:58:42.387 -E-HLD-0- la_ip_over_ip_tunnel_port_impl_fpp::set_qos_inheritance_mode() supports only PIPE/UNIFORM mode
2025 Jul 30 22:58:42.388135 sonic ERR syncd#syncd: 30-07-2025 22:58:42.387 -E-API-0- shared/src/hld/npu/la_ip_over_ip_tunnel_port_impl_fpp.cpp::2071 set_qos_inheritance_mode API returned: status = Leaba_Err: API is not implemented: virtual la_status silicon_one::gr2::la_ip_over_ip_tunnel_port_impl_fpp::set_qos_inheritance_mode(silicon_one::la_mpls_qos_inheritance_mode_e):shared/src/hld/npu/la_ip_over_ip_tunnel_port_impl_fpp.cpp:2071, 
2025 Jul 30 22:58:42.395933 sonic ERR syncd#syncd: :- sendApiResponse: api SAI_COMMON_API_CREATE failed in syncd mode: SAI_STATUS_NOT_IMPLEMENTED
2025 Jul 30 22:58:42.396117 sonic ERR syncd#syncd: :- processQuadEvent: attr: SAI_TUNNEL_TERM_TABLE_ENTRY_ATTR_VR_ID: oid:0x3000000000085
2025 Jul 30 22:58:42.396166 sonic ERR syncd#syncd: :- processQuadEvent: attr: SAI_TUNNEL_TERM_TABLE_ENTRY_ATTR_TYPE: SAI_TUNNEL_TERM_TABLE_ENTRY_TYPE_P2MP
2025 Jul 30 22:58:42.396198 sonic ERR syncd#syncd: :- processQuadEvent: attr: SAI_TUNNEL_TERM_TABLE_ENTRY_ATTR_TUNNEL_TYPE: SAI_TUNNEL_TYPE_IPINIP
2025 Jul 30 22:58:42.396227 sonic ERR syncd#syncd: :- processQuadEvent: attr: SAI_TUNNEL_TERM_TABLE_ENTRY_ATTR_ACTION_TUNNEL_ID: oid:0x2a0000000010da
2025 Jul 30 22:58:42.396265 sonic ERR syncd#syncd: :- processQuadEvent: attr: SAI_TUNNEL_TERM_TABLE_ENTRY_ATTR_DST_IP: fcbb:bbbb:1::
2025 Jul 30 22:58:42.396583 sonic ERR swss#orchagent: :- create: create status: SAI_STATUS_NOT_IMPLEMENTED
2025 Jul 30 22:58:42.396612 sonic ERR swss#orchagent: :- createMySidIpInIpTunnelTermEntry: Failed to create tunnel termination entry for MySID - -15
2025 Jul 30 22:58:42.396639 sonic NOTICE swss#orchagent: :- removeMySidIpInIpTunnel: Decreased refcount for MySID IPinIP tunnel to 0
2025 Jul 30 22:58:42.433930 sonic NOTICE swss#orchagent: :- deinitIpInIpTunnel: Removed MySID IPinIP tunnel
2025 Jul 30 22:58:42.433930 sonic ERR swss#orchagent: :- doTaskMySidTable: Failed to create/update my_sid entry for sid 32:16:0:0:fcbb:bbbb:1::

How I verified it
(will modify current mgmt test)

Details if related

[mssonicbld]

/azp run

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